Air Conditioner for vehicle

ABSTRACT

An air conditioner for a vehicle includes first and second heating heat exchangers disposed to heat air by using a cooling fluid for cooling an engine as a heat source, a heater disposed to heat the cooling fluid flowing to the second heating heat exchanger, and a controller that outputs an operation request signal to the engine when a temperature of the cooling fluid is lower than a predetermined temperature. The first and second heating heat exchangers are arranged in parallel with respect to a flow direction of the cooling fluid. In the air conditioner, the controller controls a flow amount of the cooling fluid flowing into the second heating heat exchanger to be, smaller than a flow amount of the cooling fluid flowing into the first heating heat exchanger when the heater heats the cooling fluid flowing to the second heating heat exchanger.

CROSS REFERENCE TO RELATED APPLICATION

This application is based on Japanese Patent Applications No. 2009-267179 filed on Nov. 25, 2009, No. 2010-049178 filed on Mar. 5, 2010, and No. 2010-049179 filed on Mar. 5, 2010, the contents of which are incorporated herein by reference in its entirety.

FIELD OF THE INVENTION

The present invention relates to an air conditioner for a vehicle.

BACKGROUND OF THE INVENTION

Conventionally, a vehicle air conditioner is provided with a heating heat exchanger that heats air to be blown into a vehicle compartment by using engine coolant as a heat source, for example, as in Patent Document 1 (JP 2007-278624A) or Patent Document 2 (JP 2008-126820A).

In this kind vehicle air conditioner, when the temperature of engine coolant is lower than a predetermined temperature, an operation request signal is output to an engine, even in a vehicle such as a hybrid vehicle or an idling-stop vehicle. In the vehicle such as the hybrid vehicle or the idling-stop vehicle, the engine stops in accordance with a vehicle traveling state. When the engine stops, the temperature of the engine coolant becomes lower, and it may be difficult to secure the heating capacity of air in the heating heat exchanger by using the engine coolant as the heat source. In this case, the engine is operated only for the air conditioning, so as to obtain the heating capacity of air due to the heating heat exchanger.

For example, in the vehicle air conditioner described in Patent Document 1, heat is absorbed from air in a heat pump cycle, and the engine coolant to be supplied to the heating heat exchanger is heated by using the absorbed heat of the heat pump cycle.

In the vehicle air conditioner described in Patent Document 2, an auxiliary heater using a PTC element is located downstream of the heating heat exchanger which heats air to be blown into the vehicle compartment by using the engine coolant as a heat source.

However, in the vehicle air conditioner where the operation request signal is output to the engine when the temperature of the engine coolant is lower than the predetermined temperature, fuel consumption efficiency may be deteriorated:

Furthermore, when the temperature of the engine coolant is low, the heat pump cycle may be operated instead of the engine operation, as in Patent Document 1.

When the heat pump cycle is operated for heating the engine coolant, energy is consumed by the operation of the heat pump cycle, and thereby consumed energy consumed for the heating of the engine coolant is increased.

Furthermore, when the temperature of the engine coolant is low, an auxiliary heater such as a PTC heater may be operated to directly heat air, instead of the engine operation, as in Patent Document 2. However, when the auxiliary heater is located downstream of the heating heat exchanger in an air flow, the auxiliary heater becomes a resistance in the flow of air blown into the vehicle compartment.

Alternatively, when the temperature of the engine coolant is low, the engine coolant may be heated by using a heating means other than the engine while the resistance of air blown into the vehicle compartment is not increased.

However, in a case where the engine coolant is simply heated by the heating means other than the engine, the heat quantity without being heat-exchanged with air in the heating heat exchanger may be radiated from the surface of the engine, and the heated quantity may be uselessly consumed.

This problem may be caused not only in an air conditioner for a vehicle provided with the engine, but also in an air conditioner for a vehicle provided with a driving device other than the engine, such as a fuel cell for traveling or an electrical motor for traveling.

In the air conditioner for a fuel cell vehicle provided with a fuel cell and an electrical motor, air to be blown into the vehicle compartment is heated by using coolant of the fuel cell as a heat source. In this case, when the temperature of the coolant of the fuel cell is lower than a predetermined temperature, the fuel cell is operated to generate an electrical power, and thereby energy consumed in the fuel cell becomes larger.

Furthermore, in a vehicle air conditioner described in Patent Document 3 (U.S. Pat. No. 5,337,704), as a coolant passage inside of an engine, a cylinder head passage for cooling a cylinder head and a cylinder block passage for cooling a cylinder block are used. The coolant passing through the cylinder head passage flows through a single heating heat exchanger, and is used as a heat source for a heating of a vehicle compartment.

In a vehicle air conditioner described in Patent Document 4 (EP 1008471A), two heating heat exchangers are provided for heating air, such that coolant flowing out of a single coolant outlet of an engine is branched and flows respectively into the two heating heat exchanger.

Generally, in order to reduce the size of the engine mounted to a vehicle while maintaining a required output of an engine, a compression ratio is increased, or a changing pressure is increased in the engine with a supercharger. However, if the compression ratio is increased or the charging pressure is increased in the engine with the supercharger, knocking may be caused. Thus, it may be considered to cool the cylinder head, in order to improve knocking-preventing performance.

On the other hand, it is necessary to keep the temperature of the cylinder block to be higher than a predetermined temperature, in order to reduce a friction of the cylinder block in the engine. Accordingly, the cylinder head passage and the cylinder block passage may be provided as the coolant passage of the engine, such that the flow amount of the coolant flowing in the cylinder head passage is larger than the flow amount of the coolant flowing in the cylinder block passage, as in Patent Document 3.

However, in this case, the temperature of the coolant after cooling the cylinder head may be lower than the lowest temperature required for the heating, and the temperature of air to be blown into the vehicle compartment cannot be sufficiently increased by using the coolant after passing through the cylinder head as the heat source.

Furthermore, in a vehicle where an engine efficiency is improved thereby reducing heat-generating amount of the engine, or in a hybrid vehicle, it is difficult to sufficiently heat air by using the engine coolant as the heat source.

To increase the temperature of the coolant as the heat source of the heating, a high-temperature hot water or a high-temperature fluid may be mixed with the coolant as the heat source of the heating. However, in this case, it is difficult to effectively use the heat quantity in the entire system.

In view of the above problems, it is an object of the present invention to provide a vehicle air conditioner which can effectively reduce consumed energy.

It is another object of the present invention to provide a vehicle air conditioner which can effectively perform heating operation while reducing consumed energy.

It is another object of the present application to provide an air conditioner including a heating heat exchanger provided with first and second heat exchanging portions, which can heat air to be blown into a vehicle compartment, by effectively using both a first fluid for cooling an internal combustion engine and a second fluid having a temperature higher than the first fluid.

According to an aspect of the present invention, an air conditioner for a vehicle provided with a driving unit for a vehicle traveling, includes: first and second heating heat exchangers disposed to heat air to be blown into a vehicle compartment by using a cooling fluid for cooling the driving unit as a heat source; a heater disposed to heat the cooling fluid flowing to the second heating heat exchanger in the first and second heating heat exchangers; and a controller for controlling a temperature of air to be blown into the vehicle compartment. The controller outputs an operation request signal to the driving unit when a temperature of the cooling fluid is lower than a predetermined temperature. Furthermore, the second heating heat exchanger are arranged downstream of the first heating heat exchanger in an air flow to heat air after passing through the first heating heat exchanger, and the first and second heating heat exchangers are arranged in parallel with respect to a flow direction of the cooling fluid. In the vehicle air conditioner, the controller controls a flow amount of the cooling fluid flowing into the second heating heat exchanger to be smaller than a flow amount of the cooling fluid flowing into the first heating heat exchanger when the heater heats the cooling fluid flowing to the second heating heat exchanger.

Accordingly, the temperature of the cooling fluid flowing into the second heating heat exchanger can be effectively increased by the heater, it is unnecessary to increase the temperature of the cooling fluid more than a necessary temperature required for the heating of air, by operation of the driving unit. Thus, it is possible to set a predetermined temperature, which is a basic temperature for determining whether an operation request signal is output to the driving unit, to be lower. Thus, operation frequency of the driving unit can be reduced, thereby reducing energy consumed in the driving unit. Furthermore, because only the cooling fluid flowing toward the second heating heat exchanger is heated between the first and second heating heat exchangers, the consumed energy consumed for heating the cooling fluid can be reduced. In addition, in the vehicle air conditioner, because the controller controls a flow amount of the cooling fluid flowing into the second heating heat exchanger to be smaller than a flow amount of the cooling fluid flowing into the first heating heat exchanger when the heater heats the cooling fluid flowing to the second heating heat exchanger, a ratio of heat radiation from the cooling fluid in the second heat exchanger to the heat quantity due to the heater in the cooling fluid can be effectively increased. As a result, it can restrict the heat quantity without being heat-exchanged with air in the second heating heat exchanger from being radiated from the surface of the driving unit, thereby effectively using the heat quantity due to the heating of the heater.

For example, the first and second heating heat exchangers may be configured such that a flow resistance of the cooling fluid flowing in the second heating heat exchanger is higher than a flow resistance of the cooling fluid flowing in the first heating heat exchanger.

Furthermore, a flow adjustment unit may be provided to reduce the flow amount of the cooling fluid flowing into the second heating heat exchanger when the heater is turned on to heat the cooling fluid flowing into the second heating heat exchanger, as compared with that when the heater is turned off.

Alternatively/Further, the air conditioner may be provided with a sensible heat exchanger that is configured to move heat from the cooling fluid downstream of the second heating heat exchanger to the cooling fluid upstream of the heater.

The driving unit may include an electrical motor for a vehicle traveling, and the heater may be an electrical heater which uses a high-voltage electrical source for supplying electrical power to the electrical motor, as an electrical source. Alternatively, the heater may be a heat generator, which is mounted to the vehicle separately from the driving unit, and generates heat when being operated. For example, the heat generator is an inverter which converts an electrical current supplied to the electrical motor.

According to another aspect of the present invention, an air conditioner for a vehicle provided with a driving unit for a vehicle traveling, includes: a heating heat exchanger disposed to heat air to be blown into a vehicle compartment by using a cooling fluid for cooling the driving unit as a heat source; a controller for controlling a temperature of air to be blown into the vehicle compartment, the controller outputs an operation request signal to the driving unit when a temperature of the cooling fluid is lower than a predetermined temperature; a heat absorbing portion configured to absorb heat from the cooling fluid; a heat radiating portion configured to radiate heat to the cooling fluid; and a pump portion configured to pump heat from the heat absorbing portion to the heat radiation portion. Generally, the cooling fluid has a temperature higher than outside air in winter. Thus, it is compared with a case where the pump portion pumps heat from outside air, heat radiation amount to the cooling fluid (heat source) can be increased, thereby reducing consumed energy in the pump portion.

For example, the pump portion is a Peltier element that includes a heat, absorbing surface thermally connected to the heat absorbing portion, and a heat radiating surface thermally connected to the heat radiating portion. In this case, the Peltier element absorbs heat from the heat absorbing surface and radiates heat from the heat radiating surface when direct current is applied to the Peltier element.

The heating heat exchanger may be a heat exchanger in which the cooling fluid flowing therein is heat exchanged with air passing therethrough so as to heat air. In this case, the heat absorbing portion is disposed downstream of the heating heat exchanger in a flow direction of the cooling fluid, to absorb heat from the cooling fluid flowing out of the heating heat exchanger, and the heat radiation portion is disposed upstream of the heating heat exchanger in the flow direction of the cooling fluid, to radiate heat to the cooling fluid flowing into the heating heat exchanger. Furthermore, the heating heat exchanger may include a first heater core for heating air, and a second heater core disposed to heat air after passing through the first heater core. In this case, the heat absorbing portion is disposed downstream of the second heater core in the flow direction of the cooling fluid to absorb heat from the cooling fluid flowing out of the second heater core, and the heat radiating portion is disposed upstream of the second heater core in the flow direction of the cooling fluid to radiate heat to the cooling fluid flowing into the second heater core. Here, the first and second heater cores may be arranged in parallel with respect to the flow, direction of the cooling fluid, or may be arranged in series in the flow direction of the cooling fluid.

Furthermore, a heat exchanger may be disposed to perform heat exchange between the cooling fluid before flowing into the heat radiating portion, and the cooling fluid before flowing into the heat absorbing portion at a position downstream of the second heater core in the flow direction of the cooling fluid.

A first bypass passage may be provided such that a part of the cooling fluid before flowing into the heat radiating portion is introduced into the heat absorbing portion without performing heat exchange with air in the second heater core, via the first bypass passage. Furthermore/Alternatively, a second bypass passage may be provided such that a part of the cooling fluid upstream of the heat radiating portion is introduced to the driving unit while bypassing the heat radiating portion and the heat absorbing portion, via the second bypass passage.

In the air conditioner, a first fluid circuit, in which the cooling fluid of the driving unit is circulated, may be independently provided from a second fluid circuit in which a fluid heated by the cooling fluid is circulated to flow into the heating heat exchanger.

According to another aspect of the present invention, an air conditioner for a vehicle with an internal combustion engine includes a heating heat exchanger configured to heat air to be blown into a vehicle compartment, by using a first fluid for cooling the internal combustion engine and a second fluid having a temperature higher than the first fluid, as a heat source. Furthermore, the heating heat exchanger includes a first heat exchanging portion in which the first fluid or a mixture of the first fluid and the second fluid flows, and a second heat exchanging portion in which a fluid that is mainly the second fluid and has a temperature higher than a fluid flowing into the first heat exchanging portion flows. In addition, the first heat exchanging portion and the second heat exchanging portion are integrated to form a space therebetween. Thus, air can be heated in the first heat exchanging portion by using a low temperature fluid at least including the first fluid for cooling the internal combustion engine as the heat source, and air can be heated in the second heat exchanging portion by using a high temperature fluid that is mainly the second fluid as the heat source. Accordingly, as compared with a case where air is heated by using the mixture of the first fluid and the second fluid as a heat source, the heat quantity of the second fluid can be effectively used, and thereby the temperature of air after being heated in the second heat exchanging portion can be improved.

For example, the second heat exchanging portion may be arranged downstream of the first heat exchanging portion in an air flow direction. Furthermore/Alternatively, the first heat exchanging portion and the second heat exchanging portion may be arranged in parallel with respect to an air flow direction.

The first heat exchanging portion may have a heat exchanging area in which air is heat exchanged with the fluid, and the heat exchanging area of the first heat exchanging portion may be larger than the heat exchanging area of the second heat exchanging portion.

Alternatively/Furthermore, the first heat exchanging portion and the second heat exchanging portion may be arranged such that a flowing amount of the fluid flowing in the first heat exchanging portion is larger than that flowing in the second heat exchanging portion. Furthermore, the first heat exchanging portion and the second heat exchanging portion may be configured to have respective fluid passages that are independent from each other.

The air conditioner may be provided with an air conditioning case in which the first heat exchanging portion and the second heat exchanging portion are disposed. In this case, the air conditioning case may be provided with a first air outlet from which air only having passed through the first heat exchanging portion is blown toward an inner surface of a windshield of the vehicle, and a second air outlet from which air having passed through the second heat exchanging portion is blown toward a passenger in the vehicle compartment.

In the air conditioner, the first fluid may be a cooling fluid for cooling a cylinder head of the internal combustion engine, and the second fluid may be a cooling fluid for cooling a cylinder block of the internal combustion engine. Alternatively, the first fluid may be a cooling fluid for cooling the internal combustion engine, and the second fluid may be a cooling fluid for cooling a heat generation member that is an equipment mounted to the vehicle and is different from the internal combustion engine.

BRIEF DESCRIPTION OF THE DRAWINGS

Other objects, features and advantages of the present invention will become more apparent from the following description made with reference to the accompanying drawings, in which like parts are designated by like reference numbers and in which:

FIG. 1 is a schematic diagram showing an air conditioner for a vehicle according to a first embodiment of the invention;

FIG. 2 is a block diagram showing an electric controller of the air conditioner for a vehicle in FIG. 1;

FIG. 3 is a flowchart showing a control performed by the electric controller of the air conditioner, shown in FIG. 2;

FIG. 4 is a flowchart showing a detail control at step S4 of FIG. 3;

FIG. 5 is a schematic diagram showing an air conditioner for a vehicle according to a second embodiment of the invention;

FIG. 6 is a schematic diagram showing an air conditioner for a vehicle according to a third embodiment of the invention;

FIG. 7 is a schematic diagram showing an air conditioner for a vehicle according to a fourth embodiment of the invention;

FIG. 8 is a schematic diagram showing an air conditioner for a vehicle according to a fifth embodiment of the invention;

FIG. 9 is a schematic diagram showing an air conditioner for a vehicle according to a sixth embodiment of the invention;

FIG. 10 is a schematic diagram showing an air conditioner for a vehicle according to a seventh embodiment of the invention;

FIG. 11 is a schematic diagram showing an air conditioner for a vehicle according to an eighth embodiment of the invention;

FIG. 12 is a schematic diagram showing an air conditioner for a vehicle according to a ninth embodiment of the invention;

FIG. 13 is a schematic diagram showing an air conditioner for a vehicle according to a tenth embodiment of the invention;

FIG. 14 is a schematic diagram showing an air conditioner for a vehicle according to an eleventh embodiment of the invention;

FIG. 15 is a schematic diagram showing an air conditioner for a vehicle according to a twelfth embodiment of the invention;

FIG. 16 is a block diagram showing an electric controller of the air conditioner for a vehicle in the twelfth embodiment;

FIG. 17 is a flowchart for determining ON/OFF operation of an electrical heater, according to the twelfth embodiment of the invention;

FIG. 18 is a schematic diagram showing an air conditioner for a vehicle according to a thirteenth embodiment of the invention;

FIG. 19 is a schematic diagram showing an air conditioner for a vehicle according to a fourteenth embodiment of the invention;

FIG. 20 is a perspective view showing first and second heater cores according to a fifteenth embodiment of the invention;

FIG. 21 is a schematic diagram showing an air conditioner for a vehicle according to a sixteenth embodiment of the invention;

FIG. 22 is a side view showing a heating heat exchanger according to the sixteenth embodiment;

FIG. 23 is a front view showing the heating heat exchanger according to the sixteenth embodiment;

FIG. 24 is a graph showing a temperature variation in air passing through the first and second heater cores of the heating heat exchanger according to a sixteenth embodiment of the invention;

FIGS. 25A, 25B and 25C are graphs showing a heat loss of coolant from an engine surface, an average temperature of a combustion chamber of the engine and an actual fuel consumption rate, according to the sixteenth embodiment and a comparison example (second comparison example);

FIG. 26 is a side view showing a heating heat exchanger according to a seventeenth embodiment of the invention;

FIG. 27 is a side view showing a heating heat exchanger according to an eighteenth embodiment of the invention;

FIG. 28 is a side view showing a heating heat exchanger according to a nineteenth embodiment of the invention;

FIG. 29 is a front view showing a heating heat exchanger according to the nineteenth embodiment;

FIG. 30 is a side view showing a heating heat exchanger according to a twentieth embodiment of the invention;

FIG. 31 is a front view showing a heating heat exchanger according to the twentieth embodiment;

FIG. 32 is a side view showing a heating heat exchanger according to a twenty-first embodiment of the invention; and

FIG. 33 is a schematic diagram showing an air conditioner for a vehicle according to a twenty-second embodiment of the invention.

EMBODIMENTS

Embodiments for carrying out the present invention will be described hereafter referring to drawings. In the embodiments, a part that corresponds to a matter described in a preceding embodiment may be assigned with the same reference numeral, and redundant explanation for the part may be omitted. When only a part of a configuration is described in an embodiment, another preceding embodiment may be applied to the other parts of the configuration. The parts may be combined even if it is not explicitly described that the parts can be combined. The embodiments may be partially combined even if it is not explicitly described that the embodiments can be combined, provided there is no harm in the combination.

First Embodiment

A first embodiment of the present invention will be described with reference to FIGS. 1 to 4.

FIG. 1 is a schematic diagram showing an air conditioner 1 for a vehicle according to the present embodiment of the invention, and FIG. 2 is a block diagram showing an electric controller of the air conditioner for a vehicle in the present embodiment. In the present embodiment, the air conditioner 1 for a vehicle of the invention is mounted to a so-called hybrid car which obtains a driving force for a vehicle traveling from an internal combustion engine (engine) EG and an electric motor for traveling. Thus, the engine EG is an example of a driving device for obtaining a driving force for a vehicle running in the invention.

In the hybrid vehicle of the embodiment, the engine EG is operated or stopped in accordance with a traveling load of the vehicle. Thus, the hybrid vehicle can be switched to a traveling state in which the vehicle is traveled by using driving force from both of the engine EG and the electrical motor for traveling, or a traveling state (i.e., EV traveling state) in which the vehicle is traveled only by using the electrical motor for traveling while the engine is stopped. Thus, in the hybrid vehicle, fuel consumption can be improved as compared with a vehicle driven by only the engine EG.

The air conditioner 1 for a vehicle is provided with an interior air conditioning unit 10 shown in FIG. 1, and an air conditioning controller 60 (A/C ECU) shown in FIG. 2.

The interior air conditioning unit 10 is located inside of an instrument panel (i.e., dash panel) positioned at the frontmost portion in the vehicle compartment. The interior air-conditioning unit 10 includes an air conditioning casing 11 forming an outer shell and defining an air passage. In the air conditioning casing 11, a blower 12, an evaporator 13, a first heater core 14, a second heater core 15 and the like are disposed.

The casing 11 defines the air passage through which air flows into the vehicle compartment. The casing 11 is made of a resin (e.g., polypropylene) having a suitable elasticity and being superior in the strength. An inside/outside air switching box 20 is located in the casing 11 at the most upstream side to selectively introduce inside air or/and outside air into the casing 11.

More specifically, the inside/outside air switching box 20 is provided with an inside air introduction port 21 for introducing inside air into the casing 11, and an outside air introduction port 22 for introducing outside air into the casing 11. An inside/outside air switching door 23 is disposed in the inside/outside air switching box 20 to continuously adjust open areas of the inside air introduction port 21 and the outside air introduction port 22. Therefore, the inside/outside air switching door 23 can adjust a ratio between a flow amount of inside air (i.e., air inside the vehicle compartment) introduced from the inside air introduction port 21 and a flow amount of outside air (i.e., air outside the vehicle compartment). The inside/outside air switching door 23 is driven by an electrical actuator 71, and operation of the electrical actuator 71 is controlled by a control signal output from the air conditioning controller 60.

The blower 12 is disposed in the casing 31 at a downstream air side of the inside/outside air switching box 20, to blow air drawn via the inside/outside air switching box 20 toward the interior of the vehicle compartment. The blower 12 is an electrical blower having a centrifugal multi-blade fan (e.g., sirocco fan) 12 a and an electrical motor 12 b, for example. In this case, the centrifugal multi-blade fan 12 a is driven by the electrical motor 12 b, and the rotational speed (air blowing amount) of the electrical motor 12 b is controlled by a control voltage output from the air conditioning controller 60.

The evaporator 13 is disposed in the casing 11 at a downstream air side of the blower 12 to cross all the air passage area in the casing 11. The evaporator 13 is a cooling heat exchanger in which refrigerant passing therein is heat-exchanged with air blown by the blower 12 to cool the blown air. The evaporator 12 is one component in a refrigerant cycle. The refrigerant cycle includes, for example, a compressor, a condenser, a gas-liquid separator and an expansion valve, in addition to the evaporator 13, which are generally known.

At a downstream air side of the evaporator 13, the air passage of the casing 31 is provided with a first air passage 16 through which air after passing through the evaporator 13 flows, a second air passage 17 used as a cool air bypass passage through which air after passing through the evaporator 13 flows while bypassing the first and second heater core 14, 15, and a mixing space 18 in which air from the first air passage 16 and air from the second air passage 17 are mixed.

In the first air passage 16, the first and second heater cores 14 and 15 are arranged, so that air dehumidified and cooled by the evaporator 13 flows through the first and second heater cores 14 and 15 in this order through the first air passage 16. The first heater core 14 is a first heating heat exchanger configured to perform heat exchange between engine coolant (hot water) heated by heat of the vehicle engine EG and air after passing through the evaporator 13. Thus, the first heat core 14 heats air after passing through the evaporator 13 in the first air passage 16. The second heater core 15 is a second heating heat exchanger configured to perform heat exchange between engine coolant (hot water) and air after passing through the first heater core 14. Thus, the second heat core 15 further heats air after passing through the first heater core 14 in the first air passage 16. For example, the engine coolant is water, or a water solution including addition component.

Specifically, a coolant circuit 30 is provided, so that coolant is circulated between the first and second heater cores 14, 15 and the engine EG via the coolant circuit 30. The coolant circuit 30 is provided with a coolant passage 31 adapted to the first and second heater cores 14, 15, and a coolant passage 32 adapted to a radiator 41. The coolant passages 31, 32 are connected to the engine EG in parallel with respect to a flow of the coolant from the engine EG.

The coolant passage 31 for the first and second heater cores 14, 15 is provided with a branch point 31 a, a join point 31 b, and first and second coolant passages 33, 34. The coolant flowing out of the engine EG is branched at the branch portion 31 a into the first coolant passage 33 and the second coolant passage 34, and is joined at the join point 31 b: The first heater core 14 is located in the first coolant passage 33 so that the coolant flowing into the first coolant passage 33 flows through the first heater core 14. The second heater core 15 is located in the second coolant passage 34 so that the coolant flowing into the second coolant passage 34 flows through the second heater core 15. The coolant having passed through the first and second heater cores 14, 15 respectively is joined at the join point 31 b, and returns to the engine EG. Thus, the first and second heater cores 14, 15 are arranged in parallel with respect to the flow of the engine coolant.

As shown in FIG. 1, a heat-absorption side heat exchanger 51 is located in the second coolant passage 34 at a downstream side of the second heater core 15 in the coolant flow, and a heat-radiation side heat exchanger 52 is located in the second coolant passage 34 at an upstream side of the second heater core 15 in the coolant flow. A Peltier element 53 is disposed outside of the second coolant passage 34, at a position between the heat-absorption side heat exchanger 51 and the heat-radiation side heat exchanger 52.

The heat-absorption side heat exchanger 51 is a heat exchanger for absorbing heat from the coolant, and the heat-radiation side heat exchanger 52 is a heat exchanger for radiating heat to the coolant. The heat-absorption side heat exchanger 51 and the heat-radiation side heat exchanger 52 are configured such that the flow direction of the coolant flowing through the heat-absorption side heat exchanger 51 is opposite to the flow direction of the coolant flowing through the heat-radiation side heat exchanger 52. That is, the coolant reversely flows through the heat-absorption side heat exchanger 51 and the heat-radiation side heat exchanger 52.

The Peltier element 53 is provided with a heat absorbing surface thermally connected to the heat-absorption side heat exchanger 51, and a heat radiating surface thermally connected to the heat-radiation side heat exchanger 52. When electrical current is applied to the Peltier element 53, heat is absorbed via the heat absorbing surface, and heat is radiated via the heat radiating surface. Thus, the Peltier element 53 is a heat pump system for pumping heat from the heat absorbing surface of the Peltier element 53 to the heat radiating surface of the Peltier element 53. The pumped heat quantity is adjusted by adjusting the electrical current applied to the Peltier element 53.

Because the heat-absorption side heat exchanger 51 and the heat-radiation side heat exchanger 52 are thermally connected respectively to the heat absorbing surface and the heat radiating surface of the Peltier element 53, heat is transmitted therebetween. Thus, when the direct current flows the Peltier element 53, the Peltier element 53 absorbs heat from the coolant at a coolant outlet side of the second heater core 15 via the heat-absorption side heat exchanger 51, and radiates heat to the coolant at a coolant inlet side of the second heater core 15 via the heat-radiation side heat exchanger 52. The operation of the Peltier element 53 is controlled based on the control current output from the air conditioning controller 60. Specifically, an electrical power turning on/off operation of the Peltier element 53 and an electrical current to be applied to the Peltier element 53 in the electrical power turning-on operation are controlled based on the control signal output from the air conditioning controller 60.

A thermostat 42 is located in the coolant circuit 30 at a coolant inlet side of the engine EG in the coolant circuit 30. A flow amount of the coolant flowing into the coolant passage 31 for the first and second heater cores 14, 15 and a flow amount of the coolant flowing into the coolant passage 32 for the radiator 41 are adjusted by the thermostat 42. An electrical water pump 43 is disposed in the coolant circuit 30 so that the coolant circulates in the coolant circuit 30. The operation of the water pump 43 can be controlled such that the water pump 43 is operated even when the engine EG is stopped. The water pump 43 may be operated by the power from the engine EG. In this case, the water pump 43 is also stopped when the engine EG stops.

A first coolant temperature sensor 65 is located at a coolant outlet side of the engine EG, to detect the temperature of the coolant flowing out of the engine EG. A second coolant temperature sensor 66 is located between the heat-radiation side heat exchanger 52 and the second heater core 15 in the coolant circuit 30, to detect the temperature of the coolant flowing into the second core 15.

On the other hand, cool air having passed through the evaporator 13 flows into the mixing space 18 through the second air passage 17 used as the cool air bypass passage while bypassing the first and second heater cores 14 and 15. Thus, the temperature of air (i.e., conditioned air) mixed in the mixing space 18 is changed by adjusting a ratio between a flow amount of air passing through the first air passage 16 and a flow amount of air passing through the second air passage 17.

In the present embodiment, an air mix door 19 is located on a downstream air side of the evaporator 13 at an upstream air side of the first air passage 16 and the second air passage 17, and is configured to continuously change a ratio between a flow amount of air passing through the first air passage 16 and a flow amount of air passing through the second air passage 17.

The air mix door 19 is used as a temperature adjusting unit that adjusts the air temperature in the mixing space 18 so as to adjust the temperature of conditioned air to be blown into the vehicle compartment. The air mix door 19 is driven by an electrical actuator 72, and operation of the electrical actuator 72 for the air mix door 19 is controlled by a control signal output from the air conditioning controller 60.

Furthermore, at the most downstream air side, the casing 11 is provided with plural opening portions 24, 25, 26 from which conditioned air of the mixing space 18 is blown into the vehicle compartment that is a space to be air-conditioned. For example, the plural opening portions 24, 25, 26 include a defroster opening portion 24, a face opening portion 25 and a foot opening portion 26.

A defroster duct (not shown) is connected to the defroster opening portion 24, such that conditioned air is blown toward an inner surface of a front windshield of the vehicle from a defroster air outlet provided at a downstream end of the defroster duct. A face duct (not shown) is connected to the face opening portion 25, such that conditioned air is blown toward an upper side of a passenger in the vehicle compartment from a face air outlet provided at a downstream end of the face duct. A foot duct (not shown) is connected to the foot opening portion 26, such that conditioned air is blown toward a lower side of a passenger in the vehicle compartment from a foot air outlet provided at a downstream end of the foot duct.

Air outlet mode doors for selectively switching an air outlet mode are provided in the casing 11. The air outlet mode doors include a defroster door 24 for opening and closing the defroster opening portion 24, a face door 25 a for opening and closing the face opening portion 25, and a foot door 26 a for opening and closing the foot opening portion 26. The outlet mode doors 24 a, 25 a, 26 a are driven by an electrical actuator 73, and operation of the electrical actuator 73 for the outlet mode doors 24 a, 25 a, 26 a is controlled by a control signal output from the air conditioning controller 60.

Next, an electrical control portion of the present embodiment will be described with reference to FIG. 2. The air conditioning controller 60 is configured by a very-known microcomputer including CPU, ROM, RAM, etc., and a circumference circuit of the microcomputer. The air conditioning controller 60 performs various calculations and processes based on control programs stored in the ROM, and performs control operation of various equipments connected to output of the air conditioning controller 60. For example, operation of the blower 12, the electrical actuators 71, 72, 73 and the Peltier element 53 is controlled by the air conditioning controller 60.

Air conditioning sensor group is connected to an input side of the air conditioning controller 60. For example, the air conditioning sensor group includes an inside air sensor 61 configured to detect an inside air temperature Tr of the vehicle compartment, an outside air sensor 62 configured to detect an outside air temperature Tam, a solar radiation sensor 63 configured to detect a solar radiation Ts entering into the vehicle compartment, an evaporator temperature sensor 64 configured to detect an air temperature TE blown from the evaporator 13, the first and second coolant temperature sensors 65, 66 for detecting the coolant temperature TW of the engine EG. The air temperature TE blown from the evaporator 13 corresponds to a refrigerant evaporation temperature in the evaporator 13.

An operation panel 70 is located near the instrument panel at the front portion of the vehicle compartment. The operation panel 70 is connected to the input side of the air conditioning controller 60, such that operation signals of various air-conditioning operation switches provided in the operation panel 70 are input to the air conditioning controller 60. The air-conditioning operation switches provided in the operation panel 70 include, for example, an operation switch (not shown) of the air conditioner 1, an air-conditioning switch 70 a for selectively turning on or off of the compressor thereby turning on or off of the air conditioning operation of the air conditioner 1, an automatic switch 70 b for setting or releasing an automatic control of the air conditioner 1, an operation mode selecting switch (not shown) for selecting an operation mode, a suction mode selecting switch (not shown) for selectively switching an air suction mode, an air outlet mode selecting switch (not shown) for selectively switching an air outlet mode, an air amount setting switch (not shown) for setting an air blowing amount of the blower 12, a temperature setting switch 70 c for setting a temperature of the vehicle compartment, an economic switch 70 d for outputting an economy priority mode in which the refrigerant cycle is operated with a priority of the power saving.

The air conditioning controller 60 is electrically connected to an engine controller 80 which controls operation of the engine EG. The air conditioning controller 60 and the engine controller 80 are configured to be capable of electrically communicating with each other. Based on detection signals or/and operation signals inputted from one of the engine controller 80 and the air conditioning controller 60, operation of various equipments connected to the other one of the engine controller 80 and the air conditioning controller 60 can be controlled. For example, when the air conditioning controller 60 outputs an operation request signal to the engine controller 80, the engine controller 80 causes the engine EG to be operated.

Next, the operation of the present embodiment with the above configuration will be described with reference to FIG. 3. FIG. 3 is a flowchart showing a basic control process performed by the air conditioning controller 60 in the first embodiment. The respective steps in FIG. 3 correspond to respective function portions provided in the air conditioning controller 60.

First, at step S1, initialization of a flag, a timer, a control variable, and an initial position setting of a stepping motor in respective electrical motors, and the like are performed.

At step S2, operation signals of the operation panel 70 and signals regarding the circumstances of the vehicle used for the air conditioning control, that is, detection signals from the above group of sensors 61 to 66 are read, and then the operation proceeds to step S3. Specifically, the operation signals include a vehicle interior setting temperature Tset set by the temperature setting switch 70 c, a selection signal of the air outlet mode, a selection signal of the air suction mode, a setting signal of the amount of air blown by the blower 12, and the like.

At step S3, a target outlet air temperature TAO of blown air into the vehicle compartment is calculated. The target outlet air temperature TAO of blown air into the vehicle compartment is calculated based on the vehicle interior setting temperature Tset and the vehicle environment condition such as the inside air temperature, by using the following formula F1.

TAO=Kset×Tset−Kr×Tr−Kam×Tam−Ks×Ts+C  (F1)

where Tset is a vehicle interior setting temperature set by the temperature setting switch 70 c, Tr is an inside air temperature detected by the inside air sensor 61, Tam is an outside air temperature detected by the outside air sensor 62, and Ts is an amount of solar radiation detected by the solar radiation sensor 63. The Kset, Kr, Kam, and Ks are control gains, and C is a constant for correction.

Next, at step S4, control target values of the various equipments connected to the output side of the air conditioning controller 60 are determined. For example, the air blowing amount (blower level) of the blower 12, the air suction mode, the air outlet mode, the open degree of the air mix door 19, the engine operation request signal and ON/OFF operation of the Peltier element 53 and the like are determined. The air blowing amount and the air outlet mode and the like are determined based on the target outlet air temperature TAO calculated at S3. Furthermore, the air conditioning controller 60 determines whether the engine operation request signal is output or not based on the engine coolant temperature TW. For example, when the engine coolant temperature TW detected by the first coolant temperature sensor 65 is lower than a predetermined temperature TW1, the air conditioning controller 60 outputs the engine operation request signal to the engine EG. Next, the ON/OFF operation determination of the Peltier element 53 will be described.

Then, at step S5, control signals are output from the air conditioning controller 60 to various air-conditioning control equipments or the engine controller 80, such that the control target values determined at step S4 of FIG. 3 can be obtained.

Thus, the blower 12 is operated to have a predetermined air blowing amount, the air outlet mode doors are positioned to set a desired air outlet mode, and the engine EG is operated in accordance with the engine operation request signal output from the air conditioning controller 60, for example.

Next, at step S6, it is determined whether a control period elapses. When it is determined that the control period τ elapses at step S6, the control program returns to step S2.

Next, the control process of step S4 for determining the ON/OFF operation of the Peltier element 53 will be described in detail. FIG. 4 is a flowchart for determining ON/OFF operation of the Peltier element 53, according to the present embodiment.

At step S11, a temperature TWD of air blown from the second heater core 15 is calculated. The air temperature TWD is a heated temperature of air heated by the engine coolant at least at the second heater core 15. The air temperature TWD can be calculated by the coolant temperature detected by the second coolant temperature sensor 66, the air temperature TE after passing through the evaporator 13 and the heat exchange capacity of the heater core 15 and the like. Generally, the air temperature TWD blown out of the second heater core 15 is approximately equal to the coolant temperature detected by the second coolant temperature sensor 66.

Next, at step S12, the air temperature TWD blown from the second heater core 15 is compared with the target outlet air temperature TAO. When the air temperature TWD is lower than the target outlet air temperature TAO at step S12, the Peltier element 53 is turned on at step S13. When the air temperature TWD is not lower than the target outlet air temperature TAO at step S12, the Peltier element 53 is turned off at step S14.

For example, when a long time elapses after the engine EG stops, the coolant temperature may become lower, and thereby the air temperature TWD may become lower than the target outlet air temperature TAO. In this case, in the present embodiment, electrical power is supplied to the Peltier element 53, such that heat is absorbed from the coolant after passing through the second heater core 15, and heat is radiated to the coolant flowing toward the second heater core 15. Thus, the temperature of the coolant flowing into the second heater core 15 is increased to a temperature required for the heating of the vehicle compartment. In this case, it is prefer to set the air mix door 19 at the maximum heating position, by the air conditioning controller 60.

When the engine EG is operated or an elapsed time after the stop of the engine EG is shorter, the coolant temperature is sufficiently high. In this case, if the air temperature TWD is equal to or higher than the target outlet air temperature TAO, it is unnecessary to heat the engine coolant by using the operation of the Peltier element 53. In this case, the Peltier element 53 is not turned on by the air conditioning controller 60, and the position (open degree) of the air mix degree 19 is controlled by the air conditioning controller 60, thereby adjusting the temperature of conditioned air to be blown into the vehicle compartment.

The operation effects of the first embodiment will be described.

(1) According to the present embodiment, when the air temperature TWD from the second heater core 15 is lower than the target outlet air temperature TAO, the temperature of the coolant flowing into the second heater core 15 is increased by the operation of the Peltier element 53, instead of the operation of the engine EG. Thus, the operation frequency of the engine EG can be reduced, thereby improving the fuel consumption efficiency of the engine EG, as compared with an air conditioner without having the Peltier element 53.

Because the temperature of the engine coolant is increased by the operation of the Peltier element 53, it is possible to delay the temperature decrease of the engine coolant immediately after the stop of the engine EG, and thereby a time, for which the engine coolant temperature TW detected by the first coolant temperature sensor 65 becomes equal to or higher than the engine-operation required temperature, can be made longer. Accordingly, in the present embodiment, as compared with a case where the Peltier element 53 is not provided, the operation frequency of the engine EG can be effectively reduced.

(2) Generally, the temperature of the engine coolant flowing into the second heater core 15 is preferably equal to or higher than a necessary temperature required for the heating, e.g., 60° C. On the other hand, the temperature of the coolant flowing into the interior of the engine EG is preferably equal to or higher than a lower limit temperature for effectively heating the respective parts of the engine EG. Here, the lower limit temperature is 40° C., for example.

Thus, in a conventional vehicle air conditioner without having the Peltier element 53, the engine-operation required temperature is set at a temperature around 60° C. in order to keep the coolant temperature equal to or higher than 60° C.

In contrast, according to the present embodiment, when the temperature of the engine coolant becomes lower than 60° C. while the engine EG stops, the Peltier element 53 is operated so that the temperature of the engine coolant is increased. Thus, it is possible to set the engine-operation required temperature to be lower than 60° C. For example, the engine-operation required temperature is set at a temperature about 40° C.

In the present embodiment, the engine-operation request temperature can be set at a temperature at which the necessary heating of the vehicle compartment cannot be maintained even when the Peltier element 53 is operated, or the engine-operation request temperature can be set at a temperature at which the engine EG cannot be effectively operated.

(3) In the present embodiment, the Peltier element 53 absorbs heat from the coolant of the engine EG, which is a subject to be heat-absorbed.

The subject to be heat-absorbed in the Peltier element 53 may be an outside air, instead of the coolant of the engine EG. However, when the Peltier element 53 absorbs heat from the outside air, a heat pump capacity required in the Peltier element 53 becomes larger as the outside air temperature becomes lower, and thereby the consumed electrical power of the Peltier element 53 becomes larger.

In contrast, according to the present embodiment, the Peltier element 53 absorbs heat from the engine coolant that has a temperature generally higher than the temperature of the outside air in the winter. Thus, it is possible to increase the heat radiation amount radiated from the Peltier element 53 to the coolant. As a result, the consumed power of the Peltier element 53, consumed for increasing the temperature of the coolant to a desired temperature, can be reduced.

According to the present embodiment, when the coolant temperature TW detected by the first coolant temperature sensor 65 is lower than the required temperature (40° C.) of the engine operation, the engine operation request signal is output to the engine EG: Thus, the coolant temperature can be kept at a temperature equal to or higher than the required temperature, and thereby the coolant temperature always becomes higher than the outside air temperature.

(4) when the Peltier element 53 is not provided, the coolant flowing out of the second heater core 15 flows simply into the engine EG. In this case, the heat quantity without heat-exchanged with air in the second heater core 15 is radiated from the surface of the engine EG.

In contrast, according to the present embodiment, because the heat is pumped from the coolant flowing out of the second heater core 15 by the Peltier element 53, the heat quantity without being heat exchanged with air in the second heater core 15 can be further used for the heating of the vehicle compartment. Thus, the heat quantity of the engine coolant can be effectively used.

Second Embodiment

A second embodiment of the invention will be described with reference to FIG. 5. FIG. 5 is a schematic diagram showing an air conditioner 1 for a vehicle according to the second embodiment of the invention.

In a coolant circuit 30 of the second embodiment, a second coolant passage 34 for the second heater core 15 is made different from that of the first embodiment. As shown in FIG. 5, a first bypass passage 35 is provided, such that a part of coolant flowing into the second coolant passage 34 from the branch point 31 a is directly introduced into the heat-absorption side heat exchanger 51 through the first bypass passage 35, without passing through the heat-radiation side heat exchanger 52. Furthermore, a first flow adjustment valve 36 is disposed to adjust a flow amount of the coolant flowing through the first bypass passage 35.

Specially, one end of the first bypass passage 35 is connected to an upstream side of the heat-radiation side heat exchanger 52 in the coolant flow, and the other end of the first bypass passage 35 is connected to a position of the second coolant passage 34 between a coolant outlet of the second heater core 15 and a coolant inlet of the heat-absorption side heat exchanger 51. Therefore, the coolant flowing through the first bypass passage 35 bypasses the heat-radiation side heat exchanger 52 and the second heater core 15, and flows into the heat-absorption side heat exchanger 51, without radiating heat at the heat-radiation side heat exchanger 52 and without performing heat exchange with air at the second heater core 15.

In the example of FIG. 5, the first flow adjustment valve 36 is located at a branch portion of the first bypass passage 35 branched from the coolant passage flowing through the heat radiation-side heat exchanger 52. Therefore, the flow adjustment valve 36 can easily adjust a flow amount of the coolant flowing into the heat-radiation side heat exchanger 52 and a flow amount of the coolant flowing through the first bypass passage 35. However, the first flow adjustment valve 36 may be disposed at any position in the first bypass passage 35, without being limited to the branch portion of the first bypass passage 35. For example, the first flow adjustment valve 36 may be located at a joint portion at which the downstream end of the first bypass passage 35 is joined to a coolant passage from the second heater core 15.

In the present embodiment, the air conditioning controller 60 controls the first flow adjustment valve 36, such that a part of the coolant flows into the first bypass passage 35 when the Peltier element 53 is turned on, and the flow amount of the coolant flowing through the first bypass passage 35 becomes zero when the Peltier element 53 is turned off.

According to the present embodiment, when the Peltier element 53 is turned on so that electrical current is applied to the Peltier element 53, a part of the coolant before flowing to the heat-radiation side heat exchanger 52 is introduced into the inlet side of the heat-absorption side heat exchanger 51. Therefore, the temperature of the coolant flowing into the heat-radiation side heat exchanger 52 can be approached to the temperature of the coolant flowing into the heat-absorption side heat exchanger 51. Generally, the heat radiation amount of the Peltier element 53 becomes larger, as a temperature difference between the heat absorbing surface and the heat radiating surface of the Peltier element 53 is smaller. Thus, according to the present embodiment, because the first bypass passage 35 is provided, the heat radiation amount radiated to the coolant in the heat-radiation side heat exchanger 52 can be made larger, and thereby the temperature increase of the coolant flowing into the second heater core 15 can be made larger.

According to the present embodiment, when the Peltier element 53 is turned on so that the electrical current is applied to the Peltier element 53, the air conditioning controller 60 controls the first flow adjustment valve 36, so as to adjust the flow amount of the coolant flowing through the first bypass passage 35 in accordance with the heating capacity required in the second heater core 15.

For example, when an air amount blown from an air outlet into the vehicle compartment is small, the heating capacity required in the second heater core 15 is generally small. In this case, the flow amount of the coolant flowing through the first bypass passage 35 can be made larger than the flow amount of the coolant flowing through the heat-radiation side heat exchanger 52. Thus, the flow amount of the coolant flowing into the second heater core 15 can be reduced, and thereby the temperature increase in the coolant due to the heat radiation of the heat-radiation side heat exchanger 52 can be increased.

Furthermore, when the air amount blown from the air outlet into the vehicle compartment is large, the heating capacity required in the second heater core 15 is generally large. In this case, the flow amount of the coolant flowing through the first bypass passage 35 can be made smaller than the flow amount of the coolant flowing through the heat-radiation side heat exchanger 52. In this case, the flow amount of the coolant flowing through the heat-radiation side heat exchanger 52 can be made larger, and thereby the heating capacity of the second heater core 15 can be increased.

In the above-described second embodiment, the first flow adjustment valve 36 is used to adjust the flow amount flowing through the first bypass passage 35. However, a flow switching valve may be used instead of the first flow adjustment valve 36, to switch the flow amount flowing through the first bypass passage 35 between zero and a predetermined amount larger than zero. In the above-described second embodiment, the other parts of the air conditioner 1 may be similar to those of the above-described first embodiment.

Third Embodiment

A third embodiment of the invention will be described with reference to FIG. 6. FIG. 6 is a schematic diagram showing an air conditioner 1 for a vehicle according to the third embodiment of the invention.

In the vehicle air conditioner 1 of the present embodiment, a foot passage 27 is provided through which warm air flowing out of the second heater core 15 is introduced only to the foot opening portion 26. A partition wall 11 a is disposed in the casing 11 to partition a space of the casing 11 at a downstream air side of the second heater core 15 into the foot passage 27 on a side of the foot opening portion 26 and an air passage on a side of the opening portions 24, 25. The foot passage 27 is formed by the partition wall 11 a in the casing 11.

A communication opening portion 28 is provided in the partition wall 11 a at a position immediately downstream of the second heater core 15, and an opening/closing door 28 a is disposed at the position immediately after the second heater core 15 to open and close the communication opening portion 28. When the opening/closing door 28 a opens the communication opening portion 28, the warm air flowing out of the second heater core 15 can be introduced to any the defroster opening portion 24, the face opening portion 25 and the foot opening portion 26. In contrast, when the opening/closing door 28 a closes the communication opening portion 28, the warm air flowing out of the second heater core 15 is only introduced to the foot opening portion 26.

Furthermore, the size of the first heater core 14 is made larger than the size of the second heater core 15. Specifically, the sectional area of the first heater core 14 is made larger than the sectional area of the second heater core 15, so that a part of warm air flowing out of the first heater core 14 flows to the defroster opening portion 24 and the face opening portion 25 without passing through the second heater core 15, when the opening/closing door 28 a closes the communication opening portion 28.

In the present embodiment, when the Peltier element 53 is turned on, the air conditioning controller 60 causes the opening/closing door 28 a to close the communication opening portion 28. Thus, in a foot mode in which the conditioned air is blown, from the foot air outlet and side face air outlets, the communication opening portion 28 is closed by the opening/closing door 28 a, so that air heated by the first and second heater cores 14, 15 is blown to the lower side of a passenger from the foot air outlet, and air heated by the first heater core 14 is mixed with cool air flowing through the second air passage 17 and is blown into the vehicle compartment from the side face air outlets. Thus, air conditioning with “cool-head and warm-foot” can be performed, thereby improving comfortable feeling given to a passenger in the vehicle compartment. In the above-described third embodiment, the other parts of the air conditioner 1 may be similar to those of the above-described first embodiment.

Fourth Embodiment

A fourth embodiment of the invention will be described with reference to FIG. 7. FIG. 7 is a schematic diagram showing an air conditioner 1 for a vehicle according to the fourth embodiment of the invention.

In the above-described first to third embodiments, the coolant circuit 30 is provided such that the coolant flows to the first and second heater cores 14, 15 in parallel with respect to the flow of the coolant. However, in the fourth embodiment, the coolant circuit 30 is provided such that the coolant flows to the first and second heater cores 14, 15 in series with respect to the flow of the coolant. That is, in the fourth embodiment, the first and second heater cores 14, 15 are arranged in series with respect to the flow of the coolant.

Specifically, the coolant circuit 30 is provided with a single coolant passage 31 for both the first and second heater cores 14, 15, such that the coolant flowing out of the coolant outlet of the engine EG flows through the first heater core 14 and the second heater core 15 in this order, and returns to the coolant inlet of the engine EG. Thus, the first heater core 14 is arranged upstream of the coolant flow, and the second heater core 15 is arranged downstream of the coolant flow, in the coolant circuit 30.

The heat-absorption side heat exchanger 51 is located downstream of the second heater core 15 in the coolant flow, and the heat-radiation side heat exchanger 52 is located downstream of the first heater core 14 in the coolant flow and upstream of the second heater core 15 in the coolant flow.

In the present embodiment, heat can be absorbed by the Peltier element 53 via the heat-absorption side heat exchanger 51 from the coolant after performing heat exchange with air in the second heater core 15, and heat can be radiated by the Peltier element 53 via the heat-radiation side heat exchanger 52 to the coolant flowing to the second heater core 15. Therefore, the Peltier effect can be obtained similarly to the above described first embodiment.

In the present embodiment, because the coolant after performing heat exchange with air in the first heater core 14 flows into the heat-radiation side heat exchanger 52, the heating capacity of the second heater core 15 is generally lower than the heating capacity of the first heater core 14. However, heat can be radiated by the Peltier element 53 via the heat-radiation side heat exchanger 52, the heating capacity of the second heater core 15 can be assisted by the Peltier element 53. In the above-described fourth embodiment, the other parts of the air conditioner 1 may be similar to those of the above-described first embodiment.

Fifth Embodiment

A fifth embodiment of the invention will be described with reference to FIG. 8. FIG. 8 is a schematic diagram showing an air conditioner 1 for a vehicle according to the fifth embodiment of the invention.

In the air conditioner 1 according to any one of the above-described first to fourth embodiments, two heater cores such as the first and second heater cores 14, are disposed. In the air conditioner 1 for a vehicle, a single heater core 14 is disposed to heat air to be blown into the vehicle compartment.

In the vehicle air conditioner 1, a coolant circuit 30 of the engine EG is provided such that the coolant is circulated between the heater core 14 and the engine EG. In the present embodiment, the coolant circuit 30 is provided with a coolant passage 31 for the heater core 14 and a coolant passage 32 for the radiator 41.

In the present embodiment, the heat-absorption side heat exchanger 51 is disposed in the coolant passage 31 at a downstream side of the heater core 14 in the coolant flow, and the heat-radiation side heat exchanger 52 is disposed in the coolant passage 31 at an upstream side of the heater core 14 in the coolant flow.

In the present embodiment, heat can be absorbed by the Peltier element 53 via the heat-absorption side heat exchanger 51 from the coolant after performing heat exchange with air in the heater core 14, and heat can be radiated by the Peltier element 53 via the heat-radiation side heat exchanger 52 to the coolant flowing to the second heater core 14. Therefore, the Peltier effect can be obtained similarly to the above described first embodiment. In the above-described fifth embodiment, the other parts of the air conditioner 1 may be similar to those of the above-described first embodiment.

Sixth Embodiment

A sixth embodiment of the invention will be described with reference to FIG. 9. FIG. 9 is a schematic diagram showing an air conditioner 1 for a vehicle according to the sixth embodiment of the invention. In the sixth embodiment, the features of the second embodiment described above are combined with the air conditioner 1 of the above-described sixth embodiment.

In the coolant circuit 30 of the sixth embodiment, as shown in FIG. 9, a first bypass passage 35 is provided, such that a part of coolant flowing through the coolant passage 31 is introduced into the heat-absorption side heat exchanger 51 through the first bypass passage 35, without passing through the heat-radiation side heat exchanger 52. Furthermore, a first flow adjustment valve 36 is disposed to adjust a flow amount of the coolant flowing through the first bypass passage 35. Specially, one end of the first bypass passage 35 is connected to an upstream side of the heat-radiation side heat exchanger 52 in the coolant flow, and the other end of the first bypass passage 35 is connected to a position of the coolant passage 31 between a coolant outlet of the heater core 14 and a coolant inlet of the heat-absorption side heat exchanger 51. Therefore, the coolant flowing through the first bypass passage 35 bypasses the heat-radiation side heat exchanger 52 and the heater core 14, and flows into the heat-absorption side heat exchanger 51, without radiating heat at the heat-radiation side heat exchanger 52 and without performing heat exchange with air at the heater core 14. In the example of FIG. 9, the first flow adjustment valve 36 is located at a branch portion of the first bypass passage 35 branched from the coolant passage 31. Therefore, the flow adjustment valve 36 can easily adjust a flow amount of the coolant flowing into the heat-radiation side heat exchanger 52 and a flow amount of the coolant flowing through the first bypass passage 35.

However, the first flow adjustment valve 36 may be disposed at any position in the first bypass passage 35, without being limited to the branch portion of the first bypass passage 35. The flow adjustment valve 36 is controlled by the air conditioning controller 60, similarly to the second embodiment. Thus, in the present embodiment, the effects described in the second embodiment can be obtained. In the above-described sixth embodiment, the other parts of the air conditioner 1 may be similar to those of the above-described fifth embodiment shown in FIG. 8.

Seventh Embodiment

A seventh embodiment of the invention will be described with reference to FIG. 10. FIG. 10 is a schematic diagram showing an air conditioner 1 for a vehicle according to the seventh embodiment of the invention.

In the seventh embodiment, the single heater core 14 is disposed in the casing 11 to heat air to be blown into the vehicle compartment, as in the above-described fifth embodiment of FIG. 8. In the seventh embodiment, a heat exchanger 37 is disposed, with respect to the coolant circuit 30 of the above-described fifth embodiment shown in FIG. 8. In the seventh embodiment, the heat exchanger 37 is disposed to perform heat exchange between the coolant before flowing into the heat-radiation side heat exchanger 52 and the coolant before flowing into the heat-absorption side heat exchanger 51.

The heat exchanger 37 has therein a first passage through which the coolant upstream of the heat-radiation side heat exchanger 52 flows, and a second passage through which the coolant downstream of the heater core 14 flows, so as to perform heat exchange between the coolant passing through the first passage and the coolant passing through the second passage in the heat exchanger 37. Therefore, the coolant flowing out of the heater core 14 is heated by performing heat exchange with the coolant flowing out of the engine EG, and then flows through the heat-absorption side heat exchanger 51.

Thus, the temperature of the coolant flowing into the heat-radiation side heat exchanger 52 can be approached to the temperature of the coolant flowing into the heat-absorption side heat exchanger 51. Generally, the heat radiation amount of the Peltier element 53 becomes larger, as a temperature difference between the heat absorbing surface and the heat radiating surface of the Peltier element 53 is smaller. Thus, according to the present embodiment, because the heat exchanger 37 is provided, the heat radiation amount radiated to the coolant in the heat-radiation side heat exchanger 52 can be made larger, and thereby the temperature increase of the coolant flowing into the heater core 14 can be made larger. In the above-described seventh embodiment, the other parts of the air conditioner 1 may be similar to those of the above-described fifth embodiment shown in FIG. 8.

Eighth Embodiment

An eighth embodiment of the present invention will be described with reference to FIG. 11. FIG. 11 is a schematic diagram showing an air conditioner 1 for a vehicle according to the eighth embodiment of the invention.

In a coolant circuit 30 of the eighth embodiment, as shown in FIG. 11, a second bypass passage 38 is provided, such that a part of coolant flowing through the coolant passage 31 is introduced into the coolant inlet of the engine EG, without passing through the heat-radiation side heat exchanger 52. Furthermore, a second flow adjustment valve 39 is disposed to adjust a flow amount of the coolant flowing through the second bypass passage 38.

Specially, one end of the second bypass passage 38 is connected to a coolant upstream side of the heat-radiation side heat exchanger 52 at a downstream side of the coolant outlet of the engine EG, and the other end of the second bypass passage 38 is connected to a coolant downstream side of the heat-absorption side heat exchanger 51 at an upstream side of the coolant inlet of the engine EG. Therefore, coolant flowing through the second bypass passage 38 bypasses the heat-radiation side heat exchanger 52, the heater core 14 and the heat-absorption side heat exchanger 51, and directly returns to the engine EG.

In the example of FIG. 11, the second flow adjustment valve 39 is located at a branch portion of the second bypass passage 38 branched from the coolant passage flowing through the heat radiation-side heat exchanger 52. Therefore, the flow adjustment valve 39 can easily adjust a flow amount of the coolant flowing into the heat-radiation side heat exchanger 52 and a flow amount of the coolant flowing through the second bypass passage 38. However, the second flow adjustment valve 39 may be disposed at any position in the second bypass passage 38, without being limited to the branch portion of the second bypass passage 38.

In the present embodiment, the air conditioning controller 60 controls the second flow adjustment valve 39, such that a part of the coolant flows into the second bypass passage 38 when the Peltier element 53 is turned on, and the flow amount of the coolant flowing through the second bypass passage 38 becomes zero when the Peltier element 53 is turned off.

Because heat is absorbed from the coolant by the Peltier element 53, the temperature of the coolant flowing out of the heat-absorption side heat exchanger 51 becomes lower, and thereby a temperature difference between the coolant flowing into the coolant inlet of the engine EG and the coolant outlet of the engine EG may become larger. If the temperature difference between the coolant inlet and the coolant outlet of the engine EG is large, a heat stress may be caused in the engine EG, and the engine EG may be damaged.

According to the present embodiment, when the Peltier element 53 is turned on, a part of the coolant upstream of the heat-radiation side heat exchanger 52 is introduced to the coolant inlet side of the engine EG via the second bypass passage 38. Thus, the temperature difference between the coolant flowing into the coolant inlet of the engine EG and the coolant flowing out of the coolant outlet of the engine EG can be reduced, thereby preventing a heat stress of the engine EG.

When the second bypass passage 38 is provided, the flow amount of the coolant flowing through the second coolant passage 38 may be made larger than the flow amount of the coolant flowing toward the heat-radiation side heat exchanger 52. In this case, the temperature difference between the coolant flowing into the coolant inlet of the engine EG and the coolant flowing out of the coolant outlet of the engine EG can be reduced.

In the above-described second embodiment, the second flow adjustment valve 39 is used to adjust the flow amount of the coolant flowing through the second bypass passage 38. However, a flow switching valve may be used instead of the second flow adjustment valve 38, to switch the flow amount flowing through the second bypass passage 38 between zero and a predetermined amount larger than zero. In the above-described eighth embodiment, the other parts of the air conditioner 1 may be similar to those of the above-described fifth embodiment shown in FIG. 8.

Ninth Embodiment

A ninth embodiment of the present invention will be described with reference to FIG. 12. FIG. 12 is a schematic diagram showing an air conditioner 1 for a vehicle according to the eighth embodiment of the invention.

In a coolant circuit 30 of the ninth embodiment, as shown in FIG. 12, a third bypass passage 54 and a third flow adjustment valve 55 are provided, as compared with the coolant circuit 30 of the above-described fifth embodiment shown in FIG. 8. The third bypass passage 55 is provided such that a part of coolant flowing through the coolant passage 31 is introduced into the heat-absorption side heat exchanger 51, without passing through the heat-radiation side heat exchanger 52 and the heater core 14. Furthermore, the third flow adjustment valve 55 is disposed to adjust a flow amount of the coolant flowing through the third bypass passage 54.

The coolant passage 31 for the heater core 14 is provided such that the coolant flowing out of the coolant outlet of the engine EG flows toward the heater core 14, and the coolant flowing out of the heater core 14 flows toward the coolant inlet of the engine EG. In the example of FIG. 12, the third flow adjustment valve 55 is located at a branch portion of the third bypass passage 54 branched from the coolant passage 31 flowing through the heat radiation-side heat exchanger 52.

Furthermore, the heat-absorption side heat exchanger 51 is disposed in the third bypass passage 54 so that the coolant flowing into the third bypass passage 54 flows through the heat-absorption side heat exchanger 51. Therefore, the heat-absorption side heat exchanger 51 absorbs heat from the coolant flowing out of the coolant outlet of the engine EG, and thereby the coolant after performing heat exchange with air in the heater core 14 does not flow into the heat-absorption side heat exchanger 51.

The heat-radiation side heat exchanger 52 is located downstream of the third flow adjustment valve 55 in the coolant passage 31, and upstream of the heater core 14 in the coolant flow.

In the present embodiment, the air conditioning controller 60 controls the third flow adjustment valve 55, such that the coolant flows into both the heat-absorption side heat exchanger 51 and the heat-radiation side heat exchanger 52 when the Peltier element 53 is turned on. Furthermore, the third flow adjustment valve 55 is controlled by the air conditioning controller 60 to close the third bypass passage 54 so that the coolant flows only toward the heater core 14 when the Peltier element 53 is turned off.

According to the present embodiment, when the Peltier element 53 is turned on, the coolant flowing out of the coolant outlet of the engine EG flows to both the heat-absorption side heat exchanger 51 and the heat-radiation side heat exchanger 52, and thereby the heat absorbing surface and the heat radiating surface of the Peltier element 53 have the same temperature. Thus, according to the present embodiment, the heat radiation amount of the Peltier element 53 can be effectively increased. In the above-described ninth embodiment, the other parts of the air conditioner 1 may be similar to those of the above-described fifth embodiment shown in FIG. 8.

Tenth Embodiment

A tenth embodiment of the present invention will be described with reference to FIG. 13. FIG. 13 is a schematic diagram showing an air conditioner 1 for a vehicle according to the tenth embodiment of the invention.

In the tenth embodiment, as shown in FIG. 13, a water circuit 90 is separately provided from a coolant circuit 30 for the engine EG.

The coolant circuit 30 is a closed circuit through which coolant of the engine EG is circulated between the engine EG, the heat-absorption side heat exchanger 51 and the radiator 41. The coolant flowing out of the engine EG flows through the heat-radiation side heat exchanger 51 via a coolant passage 31, and flows through the radiator 41 via a coolant passage 32.

The water circuit 90 is a circuit independently provided from the coolant circuit 30, and is provided to heat the air passing through the heater core 14 by using a hot water (fluid) as a heat source. In the present embodiment, water is circulated as an example of the fluid circulating in the water circuit 90. A water pump 92 is located in a water, passage 91 of the water circuit 90 such that hot water heated by the Peltier element 53 via the heat-radiation side heat exchanger 52 circulates in the water passage 91 of the water circuit 90.

In the present embodiment, the heat-absorption side heat exchanger 51 is disposed in the coolant circuit 30 to absorb heat from the coolant of the engine EG. In contrast, the heat-radiation side heat exchanger 52 is located in the water circuit 90 so that heat is radiated to the water in the water passage 91 of the water circuit 90. Thus, when the Peltier element 53 is turned on, the Peltier element 53 absorbs heat from the coolant of the engine EG via the heat-absorption side heat exchanger 51, and radiates heat to the water in the water circuit 90 via the heat-radiation side heat exchanger 52. Therefore, water flowing through the heat-radiation side heat exchanger 52 is heated, and the heated water flows into the heater core 14. Thus, in the present embodiment, air is heated in the heater core 14 by indirectly using the coolant of the engine EG as a heat source.

A first temperature sensor 65 is disposed in the coolant passage 31 of the coolant circuit 30 to detect the temperature of the coolant flowing out of the coolant outlet of the engine EG, and a second temperature sensor 66 is disposed in the coolant passage 91 of the water circuit 90 to detect the temperature of the water flowing into the heater core 14.

When the coolant temperature detected by the first temperature sensor 65 is lower than a required coolant temperature TW1, the air conditioning controller 60 outputs an engine operation request signal to the engine EG. For example, in the present embodiment, the required coolant temperature TW1 is set at a lower limit temperature (e.g., 40° C.) in which the engine EG can be effectively operated. Thus, in the present embodiment, the temperature of the coolant can be maintained to be equal to or higher than the lower limit temperature (e.g., 40° C.) in which the engine EG can be effectively operated.

On the other hand, in the water circuit 90, the air conditioning controller 60 controls the turning on/off operation of the Peltier element 53 such that the water temperature detected by the second temperature sensor 66 becomes equal to or higher than a temperature (e.g., 60° C.) that is higher than the lower limit temperature (e.g., 40° C.) of the engine EG.

According to the present embodiment, the heat is pumped from the coolant of the engine. EG to the water flowing into the heater core 14, so that the temperature of water flowing into the heater core 14 becomes higher than a necessary heating temperature. Thus, it is unnecessary to set the temperature of the coolant of the engine EG to be kept at a temperature equal to or higher than the necessary heating temperature. Thus, in the present embodiment, because the engine-operation required temperature can be set lower, the operation frequency of the engine EG can be reduced, and thereby the fuel consumption efficiency of the engine EG can be improved.

In the present embodiment, the Peltier element 53 absorbs heat from the coolant of the engine EG, which is a subject to be heat-absorbed. Therefore, the above effect (3) described in the first embodiment can be obtained.

Because the water circuit 90 is formed separately from the engine coolant circuit 30, it can prevent heat of the water circuit 90, without being heat-exchanged with air in the heater core 14, from being radiated at the engine.

Thus, in the present embodiment, hot water is circuited in the closed water circuit 90, and thereby all the heat pumped at the Peltier element 53 can be used for the heating of air in the heater core 14.

In the present embodiment, the single heater core 14 is provided in the casing 11 to heat air. However, in the present embodiment, two heater cores may be located similarly to the first and second heater cores of the above-described first embodiment. For example, a first heater core is located in the casing 11 at an upstream air side, and a second heater core is located in the casing 11 at a downstream air side of the first core. In this case, the coolant of the engine EG may be supplied to the first heater core, and water of the water circuit 90 shown in FIG. 13 may flow to the second heater core as in the heater core 14 of FIG. 13.

In this case, in the coolant circuit 30, a coolant passage for supplying the coolant to the first heater core and a coolant passage for the heat-absorption side heat exchanger 51 may be arranged in parallel with respect the flow of the coolant. Thus, it is possible to increase the temperature of the coolant to be supplied to both the first heater core and the heat-absorption side heat exchanger 51. In the above-described tenth embodiment, the other parts of the air conditioner 1 may be similar to those of the above-described first embodiment.

Eleventh Embodiment

An eleventh embodiment of the invention will be described with reference to FIG. 14. FIG. 14 is a schematic diagram showing an air conditioner 1 for a vehicle according to the eleventh embodiment of the invention. In the eleventh embodiment, a heat pump cycle 100 is used as a heat pump device.

Specifically, in a vehicle air conditioner 1 of the present embodiment, a heat pump cycle 100 is used instead of the Peltier element 53, as compared with the vehicle air conditioner 1 shown in FIG. 8.

The heat pump cycle 100 includes a compressor 101, a radiator 102, an expansion valve 103, a heat absorbing, unit 104, a gas-liquid separator 105 and a refrigerant pipe 106. The compressor 101 is adapted to compress refrigerant and to discharge the compressed refrigerant. The radiator 102 is disposed to cool and radiate the high-pressure refrigerant discharged from the compressor 101.

The expansion valve 103 is disposed to decompress and expand the high-pressure refrigerant flowing out of the radiator 102. The heat absorbing unit 104 is disposed so that the low pressure refrigerant decompressed by the expansion valve 103 absorbs heat in the heat absorbing unit 104. Furthermore, the gas-liquid separator 105 is disposed to separate the low-pressure refrigerant from the heat absorbing unit 104 into gas refrigerant and the liquid refrigerant, and to supply the separated gas refrigerant to a refrigerant suction side of the compressor 101.

As shown in FIG. 14, a heat-absorption side heat exchanger 51 is disposed in the coolant passage 31 at a coolant downstream side of the heater core 14 to absorb heat from the coolant, and a heat-radiation side heat exchanger 52 is disposed in the content passage 31 at a coolant upstream side of the heater core 14 to radiate heat to the coolant.

The heat absorbing unit 104 is thermally connected to the heat-absorption side heat exchanger 51, so that the refrigerant in the heat absorbing unit 104 absorbs heat from the coolant of the engine EG via the heat-absorption side heat exchanger 51. The heat radiator 102 is thermally connected to the heat-radiation side heat exchanger 52, so that the refrigerant in the heat radiator 102 radiates heat to the coolant of the engine EG via the heat-radiation side heat exchanger 52.

In the present embodiment, heat can be absorbed by the heat pump cycle 100 via the heat-absorption side heat exchanger 51 from the coolant after performing heat exchange with air in the heater core 14, and heat can be radiated by the heat pump cycle 100 via the heat-radiation side heat exchanger 52 to the coolant flowing to the heater core 14. Therefore, the effects described in the above first embodiment can be obtained.

The heat pump cycle 100 may be considered to absorb heat from air, in order to heat the coolant by using the absorbed heat.

However, when the heat pump cycle 100 absorbs heat from the outside air, a heat pump capacity required in the heat pump cycle 100 may become larger as the outside air temperature becomes lower, and thereby the consumed power of the heat pump cycle 100 may become larger.

In contrast, according to the present embodiment, the heat pump cycle 100 absorbs heat from the engine coolant that is generally higher than the temperature of the outside air in the winter. Thus, it is possible to increase the heat radiation amount radiated from the heat pump cycle 100 to the coolant. As a result, the consumed power of the heat pump cycle 100, consumed for increasing the temperature of the coolant to a desired temperature, can be reduced.

Furthermore, in the present embodiment, because heat is absorbed from the coolant having a heat transmission efficiency higher than air, the size of the heat-absorption side heat exchanger 51 can be effectively reduced.

In the present embodiment, the heat pump cycle 100 is used instead of the Peltier element 53 in the vehicle air conditioner 1 of the fifth embodiment. However, in the vehicle air conditioner 1 according to any one of the first to fourth embodiments and the sixth to tenth embodiments, the heat pump cycle 100 similarly to the eleventh embodiment may be used instead of the Peltier element 53.

In the above-described eleventh embodiment, the other parts of the air conditioner 1 may be similar to those of the above-described fifth embodiment.

Twelfth Embodiment

A twelfth embodiment of the invention will be described with reference to FIGS. 15-17. FIG. 15 is a schematic diagram showing an air conditioner 1 for a vehicle according to the twelfth embodiment of the invention. In the above-described first embodiment, the Peltier element 53 is provided in the second coolant passage 34. However, in the twelfth embodiment, the element structure of the second coolant passage 34 is changed as compared with the first embodiment shown in FIG. 1.

A water heating electrical heater 111 is disposed in the second coolant passage 34 at an upstream side of the second heater core 15 in a flow direction of the coolant in the second coolant passage 34. A flow adjustment valve 112 is disposed at a downstream side of the second heater core 15 in the flow direction of the coolant in the second coolant passage 34. Furthermore, a sensible heat exchanger 113 is disposed in the coolant passage 34 to perform heat exchange between coolants within the second coolant passage 34.

The water heating electrical heater 111 is adapted to heat the coolant before flowing into the second heater core 15 in the second coolant passage 34. For example, the water heating electrical heater 111 is an electrical heater which generates heat when an electrical power is applied thereto from a high-voltage electrical source such as a high-voltage battery or a high-voltage capacitor mounted to the vehicle. In this case, the high-voltage battery may be also used for supplying electrical power to an electrical motor for a vehicle traveling. The water heating electrical heater 111 is controlled by the air conditioning controller 60 to be turned on at a predetermined condition.

The flow adjustment valve 112 is configured such that its passage sectional area is changeable. Therefore, the flow adjustment valve 112 can adjust a flow amount of the coolant flowing through the second coolant passage 34. As the flow adjustment valve 112, an electrical valve or an electromagnetic valve may be used. In the present embodiment, the operation (e.g., open degree) of the flow adjustment valve 112 is controlled by the air conditioning controller 60 so that the flow amount of the coolant flowing through the second coolant passage 34 can be adjusted.

The sensible heat exchanger 113 is disposed in the second coolant passage 34, such that the coolant upstream of the water heating electrical heater 111 is heat exchanged with the coolant, downstream of the second heater core 15, thereby performing a heat transmission from the coolant after flowing out of the second heater core 15 to the coolant before flowing into the water heating electrical heater 111. As the sensible heat exchanger 113, a generally-known heat exchanging structure may be used.

For example, a heat pipe structure or a double pipe structure may be used as the heat exchanging structure of the sensible heat exchanger 113. In the present embodiment, the sensible heat exchanger 113 is a countercurrent-type heat exchanger in which the fluid (e.g., the coolant) flows reversely in the flow direction.

A bypass passage 114, through which the coolant flows while bypassing the sensible heat exchanger 113 at a downstream side of the second heater core 15, is provided in the second Coolant passage 34, and a flow switching valve 115 is disposed to switch a coolant path between the bypass passage 114 and a path of the sensible heat exchanger 113.

Specifically, one end of the bypass passage 114 is connected to a position between the flow adjustment valve 112 and the sensible heat exchanger 113, and the other end of the bypass passage 114 is connected to a position between the sensible heat exchanger 113 and the join point 31 b. In the present embodiment shown in FIG. 15, the flow switching valve 115 is located at an upstream end portion of the bypass passage 114 in the coolant flow. However, the flow switching valve 115 may be located at a downstream end portion of the bypass passage 114 in the coolant flow.

FIG. 16 is a schematic diagram showing an electrical control portion of the air conditioner 1 for a vehicle according to the twelfth embodiment of the invention. As shown in FIG. 16, the air conditioning controller 60 controls operation of the water heating electrical heater 111, the flow adjustment valve 112 and the flow switching valve 115, which are located at the output side of the air conditioning controller 60. The air conditioning controller 60 controls ON/OFF operation of the water heating electrical heater 111, the open degree of the flow adjustment valve 112 and the operation of the flow switching valve 115.

FIG. 17 is a flowchart for determining ON/OFF operation of the water heating electrical heater 111, according to the present embodiment. First, at step S21, an air temperature TA1 blown into the vehicle compartment from an air outlet is calculated based on the temperature TW1 of the coolant flowing into the first heater core 14 and the temperature TW2 of the coolant flowing into the second heater core 15. The temperature TW2 of the coolant flowing into the second heater core 15 can be detected by the second coolant sensor 66, and the temperature TW1 of the coolant flowing into the first heater core 14 can be detected by the first coolant sensor 65.

Next, at step S22, the air temperature TA1 calculated based on the coolant temperature at step S21 is compared with the target outlet air temperature TAO. When the air temperature TA1 is lower than the target outlet air temperature TAO at step S22, the water heating electrical heater 111 is turned on at step S23. In contrast, when the air temperature TA1 is not lower than the target outlet air temperature TAO at step S22, the water heating electrical heater 111 is turned off at step S24.

The open degree of the flow adjustment valve 112 is controlled such that the flow amount of the coolant is reduced while the water heating electrical heater 111 is turned on, as compared with the flow amount of the coolant while the water heating electrical heater is turned off. For example, when the water heating electrical heater 111 is not energized (OFF state), the open degree of the flow adjustment valve 112 is set at a first open degree such that the flow amount of the coolant flowing through the first heater core 14 is equal to the flow amount of the coolant flowing through the second heater core 15. When the water heating electrical heater 111 is energized (ON state), the open degree of the flow adjustment valve 112 is set at a second open degree such that the flow amount of the coolant flowing through the second heater core 15 is smaller than the flow amount of the coolant flowing through the first heater core 14.

Furthermore, the operation of the flow switching valve 115 is controlled, such that the coolant flows through the sensible heat exchanger 113 without flowing through the bypass passage 114 when the water heating electrical heater 111 is turned on, and the coolant only flows through the bypass passage 114 without flowing through the sensible heat exchanger 113 when the water heating electrical heater 111 is turned off.

For example, when a long time elapses after the engine EG stops, the coolant temperature may become lower, and thereby the air temperature TA1 may become lower than the target outlet air temperature TAO. That is, in this case, the coolant temperature may become lower than a necessary temperature required in the heating of the vehicle compartment.

Thus, when the coolant temperature is lower than the necessary temperature required in the heating of the vehicle compartment, the air conditioning controller 60 causes the water heating electrical heater 111 to be turned on so as to heat the coolant, and causes the flow adjustment valve 112 to be set at the second open degree so that the flow amount of the coolant flowing through the second heater core 15 is made smaller. Furthermore, in this case, the air conditioning controller 60 controls the flow switching valve 115 so that all the coolant after flowing out of the second heater core 15 flows into the sensible heat exchanger 113. Therefore, heat can be transferred from the coolant after flowing out of the second heater core 15 to the coolant before flowing into the water heating electrical heater 111. In this case, it is prefer to set the air mix door 19 at the maximum heating position, by the air conditioning controller 60.

Thus, the temperature of the coolant flowing in the second coolant passage 34 for the second heater core 15 can be controlled as follows. For example, in a case where the target temperature of air immediately after passing through the second heater core 15 is 50° C., if the coolant temperature immediately after flowing out of the engine EG is 40° C., the temperature of the coolant after passing through the sensible heat exchanger 113 is increased to 45° C. from 40° C. at the upstream side of the water-heating heat exchanger 113, and the temperature of the coolant after passing through the water heating electrical heater 111 is increased to 70° C. Because the coolant radiates heat to air in the second heater core 15, the temperature of the coolant at the coolant outlet of the second heater core 15 becomes 46° C., and is further reduced to 41° C. after passing through the sensible heat exchanger 113 at the downstream coolant side of the flow adjustment valve 112.

As described above, the temperature of the coolant flowing into the second heater core 15 can be increased without operating the engine EG, and thereby a desired heating can be performed without operating the engine EG.

When the engine EG is operated or when an elapsed time after the stop of the engine EG is short, the coolant temperature is sufficiently high. In this case, if the air temperature TA1 is equal to or higher than the target outlet air temperature TAO, it is unnecessary to heat the engine coolant by using the operation of the water heating electrical heater 111. In this case, the water heating electrical heater 111 is not turned on by the air conditioning controller 60, and the opening of the flow adjustment valve 112 is set at the first open degree so that the flow amount of the coolant flowing through the second heater core 15 is made larger. Furthermore, the flow switching valve 115 is controlled so that the coolant flowing out of the second heater core 15 flows through the bypass passage 114 without flowing through the sensible heat exchanger 113. In this case, the position (open degree) of the air mix degree 19 is controlled by the air conditioning controller 60, thereby adjusting the temperature of conditioned air to be blown into the vehicle compartment.

The operation effects of the present embodiment will be described.

(1) According to the present embodiment, when the coolant temperature is lower than the necessary temperature required for the heating of the vehicle compartment, the temperature of the coolant flowing into the second heater core 15 is increased by the operation of the water heating electrical heater 111, instead of the operation of the engine EG. Thus, the operation frequency of the engine EG can be reduced, thereby improving the fuel consumption efficiency of the engine EG, as compared with an air conditioner without having the water heating electrical heater 111.

Generally, the temperature of the engine coolant flowing into the second heater core 15 is preferably equal to or higher than the necessary temperature required for the heating, e.g., 60° C. On the other hand, the temperature of the coolant flowing into the interior of the engine EG is preferably equal to or higher than a lower limit temperature for effectively heating the respective parts of the engine EG. Here, the lower limit temperature is 40° C., for example.

Thus, in a conventional vehicle air conditioner without having the water heating electrical heater 111 and the sensible heat exchanger 113, the engine-operation required temperature is set at a temperature around 60° C. in order to keep the coolant temperature equal to or higher than 60° C.

In contrast, according to the present embodiment, when the temperature of the engine coolant becomes lower than 60° C. while the engine EG stops, the engine. EG is not operated, but the water heating electrical heater 111 is operated so that the temperature of the engine coolant is increased. Thus, in the present embodiment, it is possible to set the engine-operation required temperature to be lower than 60° C. For example, the engine-operation required temperature can be set at a temperature about 40° C. Thus, in the present embodiment, the engine operation required temperature can be set lower, and thereby the operation frequency of the engine EG can be reduced, and thereby the fuel consumption efficiency of the engine EG can be improved.

(2) In the present embodiment, the first heater core 14 and the second heater core 15 are arranged in parallel with respect to the flow of the coolant, and the heat radiation portion of the sensitive heat exchanger 113 and the water heating electrical heater 111 are arranged upstream of the second heater core 15 in the coolant flow. When the heat source for the heating of the vehicle compartment is insufficient, only the coolant flowing into the second heater core 15 is heated by the operation of the water heating electrical heater 111, thereby effectively reducing the consumed power of the water heating electrical heater 111.

Furthermore, the second heater core 15 is disposed to heat air after passing through the first heater core 14. Therefore, the air, after being heated by a low-temperature coolant in the first heater core 14, can be further heated by a high-temperature coolant heated by the water heating electrical heater 111, and thereby the heat quantity can be effectively increased for the heating of air.

(3) Furthermore, in the present embodiment, when the water heating electrical heater 111 is turned on, the flow amount of the coolant flowing through the second heater core 12 is made smaller than that when the water heating electrical heater 111 is turned off. Furthermore, when the water heating electrical heater 111 is turned on, the flow switching valve 115 is controlled so that the coolant flowing out of the second heater core 15 flows through the sensible heat exchanger 113.

However, in a case where the flow adjustment valve 112 and the sensible heat exchanger 113 are not provided, the heat quantity without being heat-exchanged with air in the second heater core 15 may be radiated from the surface of the engine EG, and the heated quantity of the water heating electrical heater 111 may be uselessly consumed.

For example, in a case where the flow amount of the coolant flowing through the first heater core 14 is the same as the flow amount of the coolant flowing through the second heater core 15, if the target temperature of air immediately after passing through the second heater core 15 is 50° C., the temperature of the coolant at the coolant outlet of the second heater core 15 is about 53° C. Thus, among the heat quantity obtained by the operation of the water heating electrical heater 111, only the heat quantity corresponding to the temperature difference of the coolant before and after heat exchange in the second heater core 15 is transferred to air, but the remaining heat quantity is uselessly radiated from the engine surface, for example.

In contrast, according to the present embodiment, the flow amount of the coolant flowing through the second heater core 15 is made smaller when the water heating electrical heater 111 is turned on, as compared with that when the water heating electrical heater 111 is turned off. Accordingly, as compared with a case where the flow amount of the coolant flowing to the second heater core 15 is larger, a ratio of the heat radiation amount from the coolant to air in the second heater core 15 can be increased with respect to the heat quantity due to the water heating electrical heater 111. Thus, in the present embodiment, the temperature of the coolant at the coolant outlet of the second heater core 15 can be decreased because of the flow adjustment valve 112 and the sensible heat exchanger 113. Generally, in a case where the heat radiation amount from the coolant to air is constant, the temperature difference of the coolant before and after the heat exchange becomes smaller as the flow amount of the coolant is larger, and the temperature difference of the coolant before and after the heat exchange becomes larger as the flow amount of the coolant is smaller.

Accordingly, in the present embodiment, it can restrict the heat quantity of the coolant, without being heat-exchanged with air in the second heater core 15, from being radiated from the surface of the engine EG. As a result, the heat quantity obtained by the water heating electrical heater 111 can be effectively used.

Furthermore, heat is transferred from the coolant flowing out of the second heater core 15 to the coolant before flowing into the water heating electrical heater 111. Therefore, in the present embodiment, it can further restrict the heat quantity of the coolant, without being heat-exchanged with air in the second heater core 15, from being radiated from the surface of the engine EG. Because the temperature of the coolant flowing into the water heating electrical heater 111 is increased by the sensible heat exchanger 113, consumed electrical power of the water heating electrical heater 111, for heating the coolant to a necessary heating temperature, can be decreased by the temperature increase of the coolant due to the sensible heat exchanger 113.

(4) In the present embodiment, the water heating electrical heater 111 can be operated by using a high-voltage electrical source for supplying an electrical power to an electrical motor for a vehicle traveling, as an electrical source.

In this case, the water heating electrical heater 111 can be located in an engine compartment of the vehicle, thereby preventing an electrical shock trouble even when a high-voltage electrical voltage is applied to the water heating electrical heater 111. Therefore, it is unnecessary to use a DC-DC converter, thereby preventing an electrical loss due to the DC-DC converter. Furthermore, because the high-voltage electrical source is used, the weight of the electrical source can be reduced as compared with that in a case where a low-voltage electrical source is used.

In the present embodiment, at steps S22, S23, when the air temperature TA1 calculated based on the coolant temperature at step S21 is lower than the target outlet air temperature TAO, it is determined that the temperature of the coolant is lower than the necessary coolant temperature required for the heating. However, when the coolant temperature detected by the first coolant sensor 65 or the second coolant temperature sensor 66 is lower than a predetermined temperature, it may be determined that the temperature of the coolant is lower than the necessary coolant temperature required for the heating. As the predetermined temperature, the engine-operation request temperature may be used.

In the present embodiment, when the water heating electrical heater 111 is turned on, the open degree of the flow adjustment valve 112 is set at the second open degree that is smaller than the first open degree. However, the open degree of the flow adjustment valve 112 may be adjusted such that all the heat quantity supplied to the coolant by the operation of the water heating electrical heater 111 can be substantially radiated to air in the second heater core 15.

In the above-described embodiment, the flow adjustment valve 112 is arranged in the second coolant passage 34 at a position downstream of the second heater core 15 in the flow direction of the second coolant. However, the flow adjustment valve 112 may be arranged in the second coolant passage 34 at a position upstream of the second heater core 15 in the flow direction of the second coolant.

In the above-described embodiment, when the water heating electrical heater 111 is turned off, the passage switching valve 115 is switched such that the coolant flows through the bypass passage 114. However, when the temperature Ta of the coolant flowing out of the second heater core 15 is lower than the temperature Tb of the coolant flowing into the water heating electrical heater 111, the flow switching valve 115 may be switched such that the coolant flows through the bypass passage 114. That is, in a condition where heat transmission, from the coolant flowing out of the second heater core 15 to the coolant flowing into the water heating electrical heater 111, cannot be performed, the flow switching valve 115 may be switched such that the coolant flows through the bypass passage 114 without flowing through the sensible heat exchanger 113.

Thirteenth Embodiment

A thirteenth embodiment of the invention will be described with reference to FIG. 18. FIG. 18 is a schematic diagram showing an air conditioner 1 for a vehicle according to the thirteenth embodiment of the invention. In the air conditioner 1 for a vehicle of the thirteenth embodiment, the sensible heat exchanger 113, the bypass passage 114 and the flow switching valve 115 are omitted with respect to the vehicle air conditioner 1 of the above-described twelfth embodiment.

Even in the case where the sensible heat exchanger 113 is omitted, when the water heating electrical heater 111 is turned on, the flow amount of the coolant flowing through the second heater core 12 is made smaller than that when the water heating electrical heater 111 is turned off. Thus, the heat radiation from the surface of the engine EG can be effectively reduced. In the above-described thirteenth embodiment, the other parts may be similar to those of above-described twelfth embodiment.

Fourteenth Embodiment

A fourteenth embodiment of the invention will be described with reference to FIG. 19. FIG. 19 is a schematic diagram showing an air conditioner 1 for a vehicle according to the fourteenth embodiment of the invention.

In the air conditioner 1 for a vehicle of the fourteenth embodiment, the water heating electrical heater 111, the sensible heat exchanger 113, the bypass passage 114 and the flow switching valve 115 are omitted, and an inverter 121 is used as a water heater instead of the water heating electrical heater 111, with respect to the vehicle air conditioner 1 of the above-described twelfth embodiment.

In the present embodiment, a coolant system is configured such that the coolant flowing out of the engine EG passes through the inverter 121, and the coolant system is switchable between a coolant passage flowing to the second heater core 15 and a inverter coolant circuit 120 that is a closed circuit.

In the inverter coolant circuit 120, the inverter 121, a water pump 122, a radiator 123, a first flow switching valve 124 and a second flow switching valve 125 are provided.

The inverter 121 is generally mounted to a hybrid vehicle to convert an electrical current, supplied from the electrical motor for a vehicle traveling, from the direct current to alternate current. The water pump 122 is disposed in the inverter coolant circuit 120 so that the coolant circulates in the inverter coolant circuit 120. The radiator 123 is a heat exchanger configured to radiate heat from the coolant after passing through the inverter 121 to air.

Specifically, the first flow switching valve 124 and the second flow switching valve 125 are disposed to be switched between a first passage in which the coolant flowing out of the engine EG passes through the inverter 121 and then flows into the second heater core 15 as in the solid line arrows in FIG. 19, and a second passage in which coolant circulates the inverter 121, the water pump 122, the radiator 123 and the inverter 121 in this order as in the chain line arrows in FIG. 19.

When the coolant temperature detected by the first coolant temperature sensor 65 is lower than a predetermined temperature, the air conditioning controller 60 causes the water pump 122 of the inverter coolant circuit 120 to be stopped, and controls the first flow switching valve 124 and the second flow switching valve 125 so that the coolant flows to the second heater core 15 through the first passage. At this time, the inverter 121 is controlled by the air conditioning controller 60 via an inverter controller, so that the converting efficiency of the inverter 121 is reduced thereby increasing the heat generating amount of the inverter 121.

Thus, when the temperature of the coolant is lower than the necessary temperature required for the heating of the vehicle compartment, the heat generation amount of the inverter 121 is increased, so that the inverter 121 can be used as a water heater.

Even when the converting efficiency of the inverter 121 is reduced, the electrical power supplied to the electrical motor for a vehicle traveling is not affected, and is hardly affected to the vehicle traveling. Thus, even when the heat generation amount of the inverter 121 is increased, the inverter 121 is cooled by the engine coolant, and the inverter element of the inverter 121 can be effectively operated.

In contrast, when the coolant temperature detected by the first coolant temperature sensor 65, located at the coolant outlet side of the engine EG, is higher than the predetermined temperature, the first flow switching valve 124 and the second flow switching valve 125 are controlled so that the coolant flows in the inverter coolant circuit 120 as in the second passage. In this case, the inverter 121 is controlled so that the converting efficiency of the inverter 121 is increased.

Thus, when the temperature of the coolant is lower than the necessary temperature required for the heating of the vehicle compartment, the coolant is circulated in the inverter coolant circuit 120, so that the inverter 121 can be cooled by the coolant. In this case, the coolant only flows through the first heater core 14 without flowing through the second heater core 15, so that air is heated by the first heater core 14.

In the present embodiment, the inverter 121 is used as the coolant heater. However, a heat generator mounted to the vehicle, using the exhaust heat of the vehicle other than the engine EG, may be used as the heat generator. For example, a motor generator mounted to a hybrid vehicle or an electrical vehicle, or a fuel cell of a hybrid vehicle provided with an engine EG and the fuel cell may be used as the heat generator. Furthermore, the coolant may be heated by using exhaust gas of the engine EG as the heat source.

Fifteenth Embodiment

A fifteenth embodiment of the invention will be described with reference to FIG. 20. FIG. 20 is a perspective view showing an integrated heat exchanger of first and second heater cores 14, 15 according to a fifteenth embodiment of the invention.

In the fifteenth embodiment; the first and second heater cores 14, 15 of the thirteenth embodiment are integrated, but the flow adjustment valve 112 of the thirteenth embodiment is removed such that the flow resistance of the coolant in the second heater core 15 is higher than the flow resistance of the coolant in the first heater core 14.

The integrated heat exchanger shown in FIG. 20 includes an inlet-side first header tank 131, an inlet-side second header tank 132, an outlet-side header tank 133, a plurality of first tubes 134 extending between the inlet-side first header tank 131 and the outlet-side header tank 133 to communicate with the inlet-side first header tank 131 and the outlet-side header tank 133, and a plurality of second tubes 135 extending between the inlet-side second header tank 132 and the outlet-side header tank 133 to communicate with the inlet-side second header tank 132 and the outlet-side header tank 133.

The inlet-side first header tank 131 extends in a tube stacking direction of the first tubes 134, so that the coolant flowing into the inlet-side first header tank 131 from a coolant inlet 131 a is distributed into the first tubes 134. Similarly, the inlet-side second header tank 132 extends in a tube stacking direction of the second tubes 135, so that the coolant flowing into the inlet-side second header tank 132 from a coolant inlet 132 a is distributed into the second tubes 135. The outlet-side header tank 133 is provided commonly for the first and second tubes 134, 135, so that the coolant having passed through the first and second tubes 134, 135 is collected in the outlet-side header tank 133.

The first heater core 14 is configured by the inlet-side first header tank 131, the first tubes 134 and the outlet-side header tank 133. The second heater core 15 is configured by the inlet-side second header tank 132, the second tubes 135 and the outlet-side header tank 133.

The second heater core 15 is configured, such that a sectional area of the coolant passage formed in the second tube 135 is smaller than a sectional area of the coolant passage formed in the first tube 134 of the first heater core 14. Thus, the flow resistance of the coolant flowing through the second heater core 15 can be made larger than the flow resistance of the coolant flowing through the first heater core 14. Alternatively/Furthermore, a passage sectional area of the second header tank 132 of the second heater core 15 on the coolant inlet side may be made smaller than a passage sectional area of the first header tank 131, such that the flow resistance of the coolant flowing in the second heater core 15 may be larger than the flow resistance of the coolant flowing in the first heater core 14.

Furthermore, in the present embodiment, a water heating electrical heater 111 is disposed in the second coolant passage 34 between the coolant inlet 132 a of the second heater core 15 and the branch point 31 a of the coolant passage 31 for the heater cores 14, 15. At the branch point 31 a, the first coolant passage 33 and the second coolant passage 34 are branched from each other.

Because the common outlet-side header tank 133 is provided for the first heater core 14 and the second heater core 15, the first heater core 14 and the second heater core 15 can be integrated by the outlet-side header tank 133. Thus, the flow resistance of the coolant flowing through the second heater core 15 can be made larger than the flow resistance of the coolant flowing through the first heater core 14, and thereby the flow amount of the coolant flowing through the second heater core 15 can be made always smaller than the flow amount of the coolant flowing through the first heater core 14.

Thus, according to the present embodiment, the flow amount of the coolant flowing through the second heater core 15 is made smaller that the flow amount of the coolant flowing through the first heater core 14 when the water heating electrical heater 111 is turned on. Accordingly, as compared with a case where the flow amount of the coolant flowing to the second heater core 15 is equal to the flow amount of the coolant flowing through the first heater core 14, a ratio of the heat radiation amount from the coolant to air in the second heater core 15 can be increased relatively with respect to the heat quantity due to the water heating electrical heater 111.

Accordingly, in the present embodiment, it can restrict the heat quantity of the coolant without being heat-exchanged with air in the second heater core 15 from being radiated from the surface of the engine EG. As a result, the heat quantity obtained by the water heating electrical heater 111 can be effectively used.

In the present embodiment, the flow resistance of the coolant flowing in the second coolant passage 34 for the second heater core 15 may be set larger than the flow resistance of the coolant flowing in the first coolant passage 33 for the first heater core 14. Even in this case, the flow resistance of the coolant flowing through the second heater core 15 can be made larger than the flow resistance of the coolant flowing through the first heater core 14. For example, the passage sectional area of the second coolant passage 34 for the second heater core 15 may be set smaller than the passage sectional area of the first coolant passage for the first heater core 14.

Sixteenth Embodiment

A sixteenth embodiment of the invention will be described with reference to FIGS. 21 to 25C. FIG. 21 is a schematic diagram showing an air conditioner 201 for a vehicle according to the sixteenth embodiment of the invention. In the present embodiment, the air conditioner 201 for a vehicle of the invention is mounted to a so-called hybrid car which obtains a driving force for a vehicle traveling from an internal combustion engine (engine) EG and an electric motor for traveling.

A coolant system of the present embodiment is provided with a first coolant circuit 210 and a second coolant circuit 220. The first coolant circuit 210 is a coolant circuit in which coolant after cooling a cylinder header 231 of an engine 230 flows. A first heater core 211, a first water pump 212 and a first temperature sensor 213 are disposed in the first coolant circuit 210. In contrast, the second coolant circuit 220 is a coolant circuit in which coolant after cooling a cylinder block 232 of the engine 230 flows. A second heater core 221, a second water pump 222 and a second temperature sensor 223 are disposed in the second coolant circuit 220. For example, the engine coolant is water, or a water solution including an addition component. The coolant for cooling the cylinder head 231 corresponds to a first fluid, and the coolant for cooling the cylinder block 232 corresponds to a second fluid. The second fluid may be the same fluid as the first fluid, or may be different from the first fluid.

In the engine 230, the cylinder block 232 is a block body forming a cylinder bore (e.g., cylindrical hole) in which a piston reciprocates. In contrast, the cylinder head 231 is a block body configured to close an opening portion at a top dead-point side of the cylinder bore, and to define the consumption chamber.

A first coolant inlet 231 a and a first coolant outlet 231 b are provided in the engine 230 at a side of the cylinder head 231. The cylinder head 231 has therein a coolant passage in which the coolant flows to cool the cylinder head 231. The coolant flowing from the first coolant inlet 231 a passes through the coolant passage within the cylinder head 231, and then flows out of the first coolant outlet 231 b.

Similarly, a second coolant inlet 232 a and a second coolant outlet 232 b are provided in the engine 230 at a side of the cylinder block 232. The cylinder block 232 has therein a coolant passage in which the coolant flows to cool the cylinder block 232. The coolant flowing from the second coolant inlet 232 a passes through the coolant passage within the cylinder block 232, and then flows out of the second coolant outlet 232 b. In the present embodiment, the coolant flows through the coolant passage within the cylinder block 232, without joining with the coolant flowing through the coolant passage within the cylinder head 231.

Each of the first heater core 211 and the second heater core 221 is a heating heat exchanger, in which the coolant flowing out of the engine 230 is heat-exchanged with air to be blown into a vehicle compartment, thereby heating air to be blown into the vehicle compartment. In the present embodiment, the first heater core 211 and the second heater core 221 are integrated so as to form a single heating heat exchanger 202. The first heater core 211 corresponds to a first heat exchanging portion of the heating heat exchanger 202, and the second heater core 221 corresponds to a second heat exchanging portion of the heating heat exchanger 202, in the present embodiment.

Furthermore, within the interior of the heating heat exchanger 202, the coolant passage of the first heater core 211 is provided independently from the coolant passage of the second heater core 221. A coolant inlet 211 a of the first heater core 211 is connected to the first coolant outlet 231 b of the cylinder head 231 via a coolant piping. On the other hand, a coolant inlet 221 a of the second heater core 221 is connected to the second coolant outlet 231 b of the cylinder block 232 via a coolant piping.

The heating heat exchanger 202 is accommodated in an air conditioning case defining an air passage through which air blown by a blower flows into the vehicle compartment. The blower may be accommodated in the air conditioning case. The heating heat exchanger 202 is disposed in the air conditioning case to form a bypass passage through which air bypasses the heating heat exchanger 202. An air mix door is disposed in the air conditioning case to adjust a mix ratio between a flow amount of air passing through the bypass passage and a flow amount of air passing through the heating heat exchanger 202.

FIGS. 22 and 23 are a side view and a front view showing the heating heat exchanger 202 of the present embodiment.

As shown in FIG. 22, the second heater core 221 is located downstream of the first heater core 211 in an air flow of the heating heat exchanger 202. In the heating heat exchanger 202, the first heater core 211 and the second heater core 221 are connected with each other by a connection member 301.

Specifically, as shown in FIGS. 22 and 23, the first heater core 211 is provided with a first inlet-side tank 211 c having the first coolant inlet 211 a, a first outlet-side tank 211 d having the first coolant outlet 211 b, a plurality of flat tubes 211 e, and corrugated heat-transmitting fins 211 f each of which is bonded to outer surfaces of adjacent flat tubes 211 e. One end of each flat tube 211 e is connected to the first inlet-side tank 211 c to communicate with the first inlet-side tank 211 c, and the other end of each flat tube 211 e is connected to the first outlet-side tank 211 d to communicate with the first outlet-side tank 211 d.

The flat tubes 211 e and the heat-transmitting fins 211 f are stacked in a stack direction to form a first heat exchanging portion 211 g. The first heater core 211 is configured in one-way flow type in which the coolant flows through all the flat tubes 211 e in one way from the first inlet-side tank 211 c to the first outlet-side tank 211 d. Thus, air passing through the first heat exchanging portion 211 g is heat exchanged with the coolant flowing in the flat tubes 211 e, to be heated by the coolant.

Similarly, the second heater core 221 is provided with a second inlet-side tank 221 c having the second coolant inlet 221 a, a second outlet-side tank 221 d having the second coolant outlet 221 b, a plurality of flat tubes 221 e, and corrugated heat-transmitting fins 221 f each of which is bonded to outer surfaces of adjacent flat tubes 221 e. One end of each flat tube 221 e is connected to the second inlet-side tank 221 c to communicate with the second inlet-side tank 221 c, and the other end of each flat tube 221 e is connected to the second outlet-side tank 221 d to communicate with the second outlet-side tank 221 d.

The flat tubes 221 e and the heat-transmitting fins 221 f are stacked in a stack direction to form a second heat exchanging core portion 221 g. The second heater core 221 is configured in one-way flow type in which the coolant flows through all the flat tubes 221 e in one way from the second inlet-side tank 221 c to the second outlet-side tank 221 d. Thus, air passing through the second heat exchanging portion 221 g is heat exchanged with the coolant flowing in the flat tubes 221 e, to be heated by the coolant.

In the first and second heater cores 211, 221, the plural flat tubes 211 e, 221 e extend in one direction that is perpendicular to the air flow direction and the stacking direction. Furthermore, the flat tubes 211 e of the first heater core 211 are arranged on one line in a stacking direction, and the flat tubes 221 e of the second heater core 221 are arranged on another one line in a stacking direction in parallel with the one line of the flat tubes 211 e at a downstream air side of the flat tubes 211 e. For example, the flat surface of the flat tube 211 e of the first heater core 211 may be parallel with the flat surface of the flat tube 221 e of the second heater core 221. Furthermore, the flat surface of the flat tube 211 e in the first heater core 211 may be substantially on the same surface as the flat surface of a corresponding flat tube 221 e in the second heater core 221. The first inlet-side tank 211 c and the first outlet-side tank 211 d respectively extend in the tube arrangement direction (i.e., stacking direction) to respectively communicate with the one ends and the other ends of the flat tubes 211 e. Similarly, the second inlet-side tank 221 c and the second outlet-side tank 221 d respectively extend in the tube arrangement direction (i.e., stacking direction) to respectively communicate with the one ends and the other ends of the flat tubes 221 e.

In the example of FIGS. 22 and 23, the inlet-side tanks 211 c, 22 c are arranged at an upper side of the flat tubes 211 e, 221 e, and the outlet-side tanks 211 d, 221 d are arranged at a lower side of the flat tubes 211 e, 221 e so that the flat tubes 211 e, 221 e extend in a top-bottom direction. Furthermore, the flat tubes 211 e, 221 e are arranged in parallel in a vehicle left-right direction in each of the first and second heater cores 211, 221. Thus, in the example of FIGS. 22 and 23, coolant flows downwardly from the top to the bottom in each of the first heater core 211 and the second heater core 221.

Furthermore, in the present embodiment, the passage cross section of the first heater core 211 on a surface perpendicular to the air flow direction has the same size as that of the second heater core 221. Thus, all air having passed through the first heater core 211 passes through the second heater core 221.

However, in the present embodiment, the dimension of the first heater core 211 is made larger than the dimension of the second heater core 221 in an air flow direction, so that the heat exchanging capacity of the first heater core 211 is made larger than that of the second heater core 221. The dimensions of the flat tubes 211 e and the heat transmitting fins 211 f of the first heater core 211 in the air flow direction are made larger than the dimensions of the flat tubes 221 e and the heat transmitting fins 221 f of the second heater core 221 in the air flow direction. Therefore, the total heat exchanging area between air and the coolant can be made larger in the first heater core 211, than that in the second heater core 221.

The passage sectional area of each flat tube 211 e of the first heater core 211 is made larger than the passage sectional area of each flat tube 221 e of the second heater core 221, and thereby the flow resistance of the coolant (fluid) flowing in the first heater core 211 is made lower than the flow resistance of the coolant (fluid) flowing in the second heater core 221. Therefore, the flow amount of the coolant flowing in the first heater core 211 can be easily set larger than the flow amount of the coolant flowing in the second heater core 221.

The connection member 301 is disposed to connect the first and second inlet-side tanks 211 c, 221 c, and to connect the first and second outlet-side tanks 211 d, 221 d. That is, the connection member 301 connects the first and second heater cores 211 and 221 with each other, at positions other than the heat-exchanging core portions 211 g, 221 g. Furthermore, in the present embodiment, the connection member 301 is adapted as a spacer for forming a space between the heat-exchanging core portions 211 g, 221 g.

Thus, the first heater core 211 and the second heater core 221 are connected to each other by the connection member 301 with a space between the heat-exchanging core portions 211 g, 221 g in the air flow direction. Therefore, it can prevent the coolant flowing in the first heater core 211 and the second heater core 221 from being directly heat-transmitted at the heat-exchanging core portions 211 g, 221 g. The connection member 301 may be made of the same material as the tanks 211 c, 221 c, 211 d, 221 d.

As shown in FIG. 21, the first temperature sensor 213 is disposed in the first coolant circuit 210, and the second temperature sensor 223 is disposed in the second coolant circuit 220. More specifically, the first temperature sensor 213 is arranged between the first coolant outlet 231 b of the engine 230 on the side of the cylinder head 231 and the coolant inlet 211 a of the first heater core 211, so as to detect the temperature of the coolant flowing out of the first coolant outlet 231 b of the engine 230 on the side of the cylinder header 231. On the other hand, the second temperature sensor 223 is arranged between the second coolant outlet 232 b of the engine 230 on the side of the cylinder block 232 and the coolant inlet 221 a of the second heater core 221, so as to detect the temperature of the coolant flowing out of the second coolant outlet 232 b of the engine 230 on the side of the cylinder block 232.

The first water pump 212 and the second water pump 222 are disposed to circulate the coolant respectively in the first and second coolant circuits 210, 220, and to adjust the flow amount of the coolant flowing in each of the first and second coolant circuits 210, 220. The first water pump 212 is arranged in the first coolant circuit 210 between the coolant outlet 211 b of the first heater core 211 and the first coolant inlet 231 a of the cylinder head 231 of the engine 230. The second water pump 222 is arranged in the second coolant circuit 220 between the coolant outlet 221 b of the second heater core 221 and the second coolant inlet 232 a of the cylinder block 232 of the engine 230.

The first water pump 212 and the second water pump 222 are electrical pumps. The rotational speeds of the first water pump 212 and the second water pump 222 are controlled so as to control respectively the flow amounts of the coolant circulating in the first coolant circuit 210 and the second coolant circuit 220. In the present embodiment, during a general operation of the engine 230, the first water pump 212 and the second water pump 222 are controlled such that the flow amount of the coolant flowing in the coolant passage of the cylinder head 231 is larger than the flow amount of the coolant flowing in the coolant passage of the cylinder block 232. Thus, it is possible to keep the temperature of the cylinder head 231 at a low temperature while improving knocking-resistance performance. At the same time, the temperature of the cylinder block 232 can be kept at a high temperature, thereby preventing a viscosity decrease of an engine oil and preventing a friction increase in the interior of the engine 230.

In the first coolant circuit 210 of the present embodiment, the coolant flowing out of the first coolant outlet 231 b of the cylinder head 231 of the engine 230 flows into the first heater core 211, is heat-exchanged with air in the first heater core 211, and then flows into the engine 230 from the first coolant inlet 231 a on the side of the cylinder head 231.

In the second coolant circuit 220 of the present embodiment, the coolant flowing out of the second coolant outlet 232 b of the cylinder head 232 of the engine 230 flows into the second heater core 221, is heat-exchanged with air in the second heater core 221, and then flows into the engine 230 from the second coolant inlet 232 a on the side of the cylinder block 232.

The first and second coolant circuits 210, 220 are configured to communicate with a radiator (not shown), such that the coolant flowing out of the cylinder head 231 is radiated in the radiator and the coolant after heat radiation flows into the cylinder head 231, and the coolant flowing out of the cylinder block 232 is radiated in the radiator and the coolant after heat radiation flows into the cylinder block 232.

Next, operation of the air conditioner 201 according to the present embodiment will be described.

In the present embodiment, the first water pump 212 and the second water pump 222 are controlled by the controller such that the flow amount of the coolant flowing in the coolant passage of the cylinder head 231 is larger than the flow amount of the coolant flowing in the coolant passage of the cylinder block 232.

Furthermore, in a heating operation of the vehicle compartment (i.e., a space to be heated), the blower is controlled by the controller to an air blowing amount that is determined in accordance with a target outlet air temperature TAO. The target outlet air temperature TAO is a target temperature of air to be blown into the vehicle compartment, and can be calculated based on a set temperature and an air-conditioning load relative to the environmental conditions. For example, the target outlet air temperature TAO can be calculated similarly to that of the above-described first embodiment.

FIG. 24 is a graph showing a temperature variation in air passing through the first and second heater cores 211, 221 according to the sixteenth embodiment, and a comparison example.

In the first heater core 211, the coolant after cooling the cylinder head 231 is heat-exchanged with air passing therethrough, thereby heating the air. The temperature of the coolant after cooling the cylinder head 231 may be lower than the lowest temperature required for the heating. However, the flow amount of the coolant flowing in the cylinder head 231 is relatively large, and thereby the coolant having a large heat quantity flows into the first heater core 211 from the cylinder head 231. In the present embodiment, the flow amount of the coolant flowing in the first heater core 211 is made larger than the flow amount of the coolant flowing in the second heater core 221, and the heat exchanging area of the first heater core 211 is made larger than the heat exchanging area of the second heater core 221. Therefore, a large amount of heat quantity of the coolant after cooling the cylinder head 231 can be transferred to air in the first heater core 211. Therefore, a large amount of heat quantity can be supplied from the large amount coolant after passing through the cylinder head 231 to air. As a result, the temperature of air A1 after passing through the first heater core 211 can be approached to a coolant temperature Th1 before flowing into the first heater core 211. For example, the coolant temperature Th1 is a coolant temperature at the coolant inlet 211 a of the first heater core 211, as shown in FIG. 24.

In the second heater core 221, the coolant after cooling the cylinder block 232 is heat-exchanged with air A1 having passed through the first heater core 211, thereby further heating the air A1. The coolant after cooling the cylinder block 232 has a high temperature higher than the temperature of the coolant after cooling the cylinder head 231. Therefore, the air A1 after passing through the first heater core 211 can be further heated by the second heater core 221, and the temperature of air A2 after passing through the second heater core 221 can be increased to a temperature higher than the temperature of air A1. As shown in FIG. 24, the temperature of the air A2 after passing through the second heater core 221 can be increased to a temperature near a coolant temperature Th2 flowing into the coolant inlet 221 a of the second heater core 221.

In a comparison example 1 shown in FIG. 24, coolant after cooling the cylinder head 231 and coolant after cooling the cylinder block 232 are joined in the interior of the engine, and the joined coolant flows into a single heater core from a single coolant outlet provided in the engine. In the comparison example 1, the flow amount of the coolant flowing in the cylinder head is made larger than the flow amount of the coolant flowing in the cylinder block. However, in the comparison example 1, the temperature of air cannot be sufficiently increased, as compared with the present embodiment.

In contrast, according to the present embodiment, the first and second coolant circuits 210, 220 are independently provided as two separate coolant systems. Furthermore, the first water pump 212 and the second water pump 222 are controlled such that the flow amount of the coolant flowing in the coolant passage of the cylinder head 231 is larger than the flow amount of the coolant flowing in the coolant passage of the cylinder block 232, in the general operation of the engine 230. Therefore, in the general operation of the engine 230, the cylinder head 231 can be effectively cooled. Thus, the temperature of the coolant after cooling the cylinder head 231 may be lower than the lowest temperature required for the heating, but the temperature of the coolant after cooling the cylinder block 232 can become higher than the lowest temperature required for the heating.

If the coolant after passing through the cylinder head 231 and the coolant after passing through the cylinder block 232 are completely mixed as in the comparison example 1 of FIG. 24, the temperature of the mixed coolant may become lower than the lowest temperature required for the heating. In this case, the heat transmitting efficiency from the coolant to air becomes lower, and thereby the temperature of air cannot be sufficiently heated by using the mixed coolant as the heat source.

In the present embodiment, the first coolant outlet 231 b and the second coolant outlet 232 b are provided in the engine 230, such that low temperature coolant after cooling the cylinder head 231 flows out of the first coolant outlet 231 b, and high temperature coolant after cooling the cylinder block 232 flows out of the second coolant outlet 232 b. Thus, the low temperature coolant flowing out of the first coolant outlet 231 b flows into the first heater core 211, and the high temperature coolant flowing out of the second coolant outlet 232 b flows into the second heater core 221, without mixing therebetween.

In the present embodiment, the air having passed through the first heater core 211 is heated by using the high temperature coolant flowing out of the second coolant outlet 232 b as the heat source in the second heater core 221. Thus, the temperature of air after being heated in the first heater core 211 can be effectively increased by the second heater core 221, as compared with a case where the air is heated by only using the low temperature coolant flowing out of the first coolant outlet 231 b or a case where the air is heated by using the mixture of the low temperature coolant and the high temperature coolant as the heat source.

In the present embodiment, after air is heated by the low temperature coolant as the heat source in the first heater core 211, the heated air is further heated by the high temperature coolant as the heat source in the second heater core 221, thereby effectively using both of heat quantities of the low temperature coolant and the high temperature coolant.

Thus, in the present embodiment, the energy transmission efficiency from the coolant to air in the entire first and second heater cores 211, 221 can be effectively increased, as compared with a case where the air to be blown into the vehicle compartment is heated by using the mixture of the coolants flowing out of the first and second coolant outlets 231 b, 232 b as the heat source in a single heater core.

As a result, even when the air blowing amount of the blower is large, the air can be sufficiently heated to a high temperature, thereby effectively performing the heating of the passenger compartment.

Furthermore, in the present embodiment, the fuel consumption amount consumed in the vehicle air conditioner can be reduced as shown in FIGS. 25A, 25B and 25C. FIGS. 25A, 25B and 25C show heat loss of the coolant from the surface of the engine 230, an average temperature in a combustion chamber of the engine 230 and an actual fuel combustion rate, in the sixteenth embodiment and a comparison example 2. In the comparison example 2, the flow amount of the coolant flowing to the cylinder head 231 is made the same as the flow amount of the coolant flowing to the cylinder block 232, and the temperature of the coolant after cooling the cylinder head 231 is made equal to the temperature of the coolant after cooling the cylinder block 232.

According to the present embodiment, the heating heat quantity can be made the same as the comparison example 2, while heat loss from the cylinder head 231 of the engine 230 can be reduced, as shown in FIG. 25A.

Furthermore, in the present embodiment, the average temperature in the combustion chamber of the engine 230 can be reduced as compared with the comparison example 2, as shown in FIG. 25B. Therefore, in the present embodiment, the fuel consumption rate can be reduced as compared with the comparison example 2, as shown in FIG. 25C.

Seventeenth Embodiment

A seventeenth embodiment of the invention will be described with reference to FIG. 26. FIG. 26 is a side view showing a heating heat exchanger 202 of the seventeenth embodiment. In the present embodiment, a common outlet-side tank is provided with respect to the heating heat exchanger 202 described in the sixteenth embodiment.

Specifically, in the heating heat exchanger 202 of the present embodiment, as shown in FIG. 26, a common tank 202 d is provided to connect a coolant outlet side of the first heat-exchanging core portion 211 g of the first heater core 211 and a coolant outlet side of the second heat-exchanging core portion 221 g of the second heater core 221. Furthermore, the common tank 202 d is provided, with a single coolant outlet 202 b.

Thus, the low temperature coolant flowing from the coolant inlet 211 a of the first heater core 211 and the high temperature coolant flowing from the coolant inlet 221 a of the second heater core 221 are joined in the common tank 202 d, and then the joined coolant flows out of the single coolant outlet 202 b.

Therefore, the coolant after passing through the first heat-exchanging core portion 211 g of the first heater core 211 and the coolant after passing through the second heat-exchanging core portion 221 g are joined adjacent to the coolant outlet 202 b of the heating heat exchanger 202.

In the present embodiment, the coolant flowing out of the coolant outlet 202 b of the common tank 202 d is branched at a coolant branch portion, and then the branched coolants respectively flow into the first coolant inlet 231 a and the second coolant inlet 232 a of the engine 230. In the present embodiment, the other parts may be similar to those of the above-described sixteenth embodiment.

Eighteenth Embodiment

An eighteenth embodiment of the invention will be described with reference to FIG. 27. FIG. 27 is a side view showing a heating heat exchanger 202 of the eighteenth embodiment. In the present embodiment, as shown in FIG. 27, a common tank 202 d is provided to connect a coolant inlet side of the first heat-exchanging core portion 211 g of the first heater core 211 and a coolant outlet side of the second heat-exchanging core portion 221 g of the second heater core 221. That is, a coolant inlet 202 a of the first heater core 211 is provided in the common tank 202 d used in common for the first and second heater cores 211, 221, and an outlet side tank 211 d of the first heater core 211 is provided adjacent to the inlet side tank 221 c of the second heater core 221.

The coolant inlet 202 a provided in the common tank 202 d is connected to the first coolant outlet 231 b of the cylinder head 231 of the engine 230 shown in FIG. 21 via piping.

Thus, the high temperature coolant having passed through the second heat-exchanging core portion 221 g of the second heater core 221 is joined with low temperature coolant flowing from the first coolant outlet 231 b of the engine 230 to the coolant inlet 202 a in the common tank 202 d. Then, the joined coolant flows through the first heat-exchanging core portion 211 g of the first heater core 211 from the common tank 202 d, and thereafter flows out of the coolant outlet 211 b provided in the outlet side tank 211 d of the first heater core 211.

Accordingly, in the present embodiment, the high temperature coolant flows through the second heater core 221, and the mixture of the low temperature coolant from the first coolant outlet 231 b of the engine 230 and the high temperature coolant having passed through the second heater core 221 flows into the heat-exchanging core portion 211 g of the first heater core 211. Therefore, the temperature of the coolant flowing in the second heater core 221 can be made higher than the temperature of the coolant flowing in the heat-exchanging core portion 211 g of the first heater core 211, thereby effectively performing the heating of air to be blown into the vehicle compartment. In the present embodiment, the other parts may be similar to those of the above-described sixteenth embodiment.

Nineteenth Embodiment

A nineteenth embodiment of the invention will be described with reference to FIGS. 28 and 29. FIGS. 28 and 29 are a side view and a front view showing a heating heat exchanger 202 disposed in an air conditioning case 203 of the present embodiment.

In the heating heat exchanger 202 of the present embodiment, the first heater core 211 and the second heater core 221 are arranged in parallel with respect to a flow direction of air passing through the air passage in the air conditioning case 203. In the examples of FIGS. 28 and 29, the first heater core 211 is arranged at an upper side in the air passage of the air conditioning case 203, and the second heater core 221 is arranged at a lower side in the air passage of the air conditioning case 203, in a top-bottom direction of the vehicle. A lower end portion of the first heater core 211 is connected to an upper end portion of the second heater core 221 by a connection member 301, such that a space is formed between the first heater core 211 and the second heater core 221.

A partition wall 203 a is provided in the air conditioning case 203 at a position downstream of the heating heat exchanger 202, so as to partition the air passage of the air conditioning case 203 into a first passage communicating with a defroster air outlet 204 a (DEF) and a second passage communicating with a foot air outlet 204 b (FOOT). In the present embodiment, conditioned air is blown toward an inner surface of a windshield of the vehicle through the defroster air outlet 204 a that is adapted as a first air outlet, and conditioned air is blown toward a lower side of a passenger in the vehicle compartment through the foot air outlet 204 b that is adapted as a second air outlet. The first passage communicating with the defroster air outlet 204 a is positioned at an upper side, and the second passage communicating with the foot air outlet 204 b is positioned at a lower side in the air conditioning case 203, in the vehicle top-bottom direction. Thus, air B1 after passing through the first heater core 211 mainly flows to the first passage communicating with the defroster air outlet 204 a, and air 82 after passing through the second heater core 221 mainly flows to the second passage communicating with the foot air outlet 204 b.

Furthermore, in the present embodiment, the structure of the first heater core 211 and the structure of the second heater core 221 are respectively similar to those in the above-described sixteenth embodiment.

In the examples of FIGS. 28 and 29, the thickness of the first heater core 211 in the air flow direction is the same as the thickness of the second heater core 221, but the dimensions of the heat exchanging core portions 211 g and 221 g in the vehicle top-bottom direction are made to be different from each other. Specifically, the dimension of the flat tube 211 e and the heat transmitting fin 211 f extending in the vehicle top-bottom direction is made longer than the dimension of the flat tube 221 e and the heat transmitting fin 221 f extending in the vehicle top-bottom direction. Therefore, the heat exchanging area between air and the coolant can be made larger in the first heater core 211, than that in the second heater core 221.

Accordingly, the passage sectional area of each flat tube 211 e of the first heater core 211 can be made larger than the passage sectional area of each flat tube 221 e of the second heater core 221, and thereby the flow resistance of the coolant (fluid) flowing in the first heater core 211 can be made lower than the flow resistance of the coolant (fluid) flowing in the second heater core 221.

Thus, in the present embodiment, in a heating operation, the air to be blown to the defroster air outlet 204 a can be heated by using a large amount coolant after cooling the cylinder head 231, as the heat source. In contrast, in the heating operation, the air to be blown to the foot air outlet 204 a can be heated by using the high temperature coolant after cooling the cylinder block 232, as the heat source.

Accordingly, relatively low-temperature warm air can be blown toward the windshield from the defroster air outlet, and at the same time, relatively high-temperature warm air can be blown toward the passage from the foot air outlet. Therefore, it is possible to set a temperature difference between the temperature of air blown to the defroster air outlet and the temperature of air blown to the foot air outlet.

Twentieth Embodiment

A twentieth embodiment of the invention will be described with reference to FIGS. 30 and 31. FIGS. 30 and 31 are a side view and a front view showing a heating heat exchanger 202 of the present embodiment. In the present embodiment, as shown in FIGS. 30 and 31, a single coolant outlet is provided with respect to the heating heat exchanger 202 of the above-described nineteenth embodiment shown in FIGS. 28 and 29.

Specifically, in the heating heat exchanger 202 of the present embodiment, communication portions 302, 303 are provided to communicate the outlet side tank 211 d of the first heater core 211 and the outlet side tank 221 d of the second heater core 221 with each other, without providing a special coolant outlet in the outlet side tank 211 d of the first heater core 211.

Thus, in the present embodiment, the coolant after passing through the heat-exchanging core portion 211 g of the first heater core 211 flows into the communication portions 302, 303, and is joined with the coolant after passing through the heat-exchanging core portion 221 g of the second heater core 221 in the outlet side tank 221 d of the second heater core 221. Then, the joined coolant flows out of heating heat exchanger 202 from the coolant outlet 221 b of the outlet side tank 221 d of the second heater core 221.

As described above, even in the heating heat exchanger 202 in which the first heater core 211 and the second heater core 221 are arranged in parallel with respect to the air flow direction, the coolant after passing through the first heat-exchanging core portion 211 g of the first heat core 211 and the coolant after passing through the second heat-exchanging core portion 221 g of the second heater core 221 can be joined at a portion adjacent to the coolant outlet 221 b of the heating heat exchanger 202.

Twenty-First Embodiment

A twenty-first embodiment of the invention will be described with reference to FIG. 32. FIG. 32 is a side view showing a heating heat exchanger 202 of the twenty-first embodiment. The twenty-first embodiment corresponds to a combination of the above-described sixteenth embodiment and nineteenth embodiment. That is, the partition wall 203 a, the defroster air outlet 204 a and the foot air outlet 204 b are provided similar to the nineteenth embodiment shown in FIG. 28. Specifically, as shown in FIG. 32, a first heater core 211 is disposed in the air conditioning case 203 to across all the air passage of the air conditioning case 203, and a second heater core 221 is located in the air conditioning case 203 downstream of the first heater core 211 in the air flow direction to be opposite to a part of the downstream surface of the first heater core 211. Thus, a part of air having passed through the first heater core 211 flows into the second heater core 221, and the other part of air having passed through the first heater core 211 bypasses the second heater core 221.

The dimension of the heat-exchanging core portion 221 g of the second heater core 221 in the top-bottom direction is made shorter than the dimension of the heat-exchanging core portion 211 g of the first heater core 211 in the top-bottom direction, and is arranged at the lower side in the air passage of the air conditioning case 203.

Therefore, in the heating operation of the present embodiment, a relatively low-temperature air heated by only the first heater core 211 can be blown toward the defroster air outlet 204 a, and relatively high-temperature air heated by both the first heater core 211 and the second heater core 221 can be blown toward the foot air outlet 204 b. As a result, the temperature of air to be blown into the foot air outlet 204 b can be more increased as compared with the nineteenth embodiment. In the present embodiment, other parts may be similar to those of the above-described sixteenth embodiment.

Twenty-Second Embodiment

A twenty-second embodiment of the invention will be described with reference to FIG. 33. FIG. 33 is a schematic diagram showing an air conditioner for a vehicle according to the twenty-second embodiment of the invention. In the above-described sixteenth to twenty-first embodiments, the coolant after cooling the cylinder head 231 of the engine 230 is used as the low-temperature side coolant, and the coolant after cooling the cylinder block 232 of the engine 230 is used as the high-temperature side coolant. However, in the twenty-second embodiment, coolant of the engine 230 is used as the low temperature coolant, and coolant of an inverter 241 is used as the high temperature coolant. Thus; the coolant of the engine 230 corresponds to the first fluid, and the coolant of the inverter 241 corresponds to the second fluid.

As shown in FIG. 33, a heating heat exchanger 202 of the present embodiment includes a first heater core 211 arranged at an upstream air side in an air conditioning case 203, and a second heater core 221 arranged at a downstream air side of the first heater core 211 in the air conditioning case 203, similarly to the above-described sixteenth embodiment.

The first heater core 211 is disposed in an engine coolant circuit so that the coolant after cooling the engine 230 flows into the first heater core 211. Thus, a single coolant outlet is provided for the heating heat exchanger 202, in the engine 230.

On the other hand, the second heater core 221 is provided in an inverter coolant circuit 240, so that the coolant in the inverter coolant circuit 240 flows into the second heater core 221. The inverter coolant circuit 240, in which the coolant for cooling the inverter 241 circulates, is a coolant circuit provided independently from the engine coolant circuit. The inverter coolant circuit 240 is provided with the inverter 241, a water pump 242, a radiator 243, a thermostat 244.

The inverter 241 is an electrical machine mounted to a hybrid vehicle, and is adapted to convert an electrical current supplied to an electrical motor for a vehicle traveling from the direct current to the alternate current. The water pump 242 is disposed in the inverter coolant circuit 240 so that the coolant circulates in the inverter coolant circuit 240. The radiator 243 is a heat exchanger configured to radiate heat from the coolant after passing through the inverter 241 to air. The thermostat 244 is a flow opening/closing unit that opens or closes a coolant passage through which the coolant flows to the radiator 243.

Generally, in the hybrid vehicle, the engine 230 may be stopped in accordance with a traveling load of the vehicle.

In the present embodiment, if a controller (not shown) determines that the temperature of the coolant flowing out of the engine 230 is lower than a necessary lowest temperature required for the heating in the beating operation and determines that the temperature of air after passing through the first heater core 211 cannot be sufficiently increased, a converting efficiency of the inverter 241 is decreased so that the inverter 241 is adapted as a heat generating member. Thus, the temperature of the coolant flowing into the second heater core 221 can be made higher than the temperature of the coolant flowing into the first heater core 211, thereby further increasing the temperature of air to be blown toward the vehicle compartment. Furthermore, in a case where the temperature of the coolant of the inverter 241 is too increased, the coolant in the inverter coolant circuit is cooled by the radiator 243, thereby preventing a trouble caused in the inverter 241.

In the present embodiment, as the high temperature coolant, the coolant of the inverter 241 is used. However, coolant of a heat generator mounted to the vehicle to use the exhaust heat of the vehicle, other than the engine EG, may be used as the high temperature coolant. For example, coolant, for cooling an electrical machine such as a generator and a battery mounted on a hybrid vehicle or an electrical vehicle, may be used as the heat source for the heating of air to be blown into the vehicle compartment.

Furthermore, hot water of a hot water circuit heated by a heating unit other than the engine may flow into the second heater core 221. As the heating unit, a water-heating electrical heater, a heat pump, an exhaust heat of an exhaust gas or the like may be used. In this case, it is prefer for the flow amount of the coolant flowing through the second heater core 221 to be smaller than the flow amount of the coolant flowing through the first heater core 211. In the above-described twenty-second embodiment, the inverter coolant circuit is configured separately from the engine coolant circuit. However, the inverter coolant circuit may be configured to be connected to the engine coolant circuit, so that a part of the engine coolant circuit flows into the inverter coolant circuit.

Other Embodiments

Although the present invention has been fully described in connection with the preferred embodiments thereof with reference to the accompanying drawings, it is to be noted that various changes and modifications will become apparent to those skilled in the art.

(1) In the above-described embodiments, the air conditioner according to the invention is used for a hybrid car having an engine EG and an electrical motor for a vehicle traveling. However, the air conditioner according to the invention may be suitably used for an idling-stop vehicle or other kinds of vehicles such as a fuel cell vehicle or an electrical vehicle that has a vehicle driving source other than the engine EG.

For example, in the air conditioner for a fuel cell vehicle provided with a fuel cell and an electrical motor, air to be blown into the vehicle compartment is heated in a heating heat exchanger by using coolant of the fuel cell as a heat source.

(2) In the above-described sixteenth embodiment, the heat-exchanging core portion 211 g of the first heater core 211 and the heat-exchanging core portion 221 g of the second heater core 221 are spaced from each other in the air flow direction in the whole area of the heat-exchanging core portions 211 g, 221 g. However, the heat-exchanging core portion 211 g of the first heater core 211 and the heat-exchanging core portion 221 g of the second heater core 221 may be partially spaced from each other so that a part area can be connected therebetween. Even in this case, the heat transmission between the heat-exchanging core portion 211 g of the first heater core 211 and the heat-exchanging core portion 221 g of the second heater core 221 can be reduced as compared with a case where the all area are connected to each other.

(3) In the above-described sixteenth embodiment, the flow direction of the coolant in the first heater core 211 is made the same as that in the second heater core 221, such that the coolant flows from the top side to the bottom side in the heat-exchanging core portions 211 g, 221 g. However, the flow direction of the coolant in the first heater core 211 can be made reversely to the flow direction of the coolant in the second heater core 221.

(4) In the above-described nineteenth to twenty-first embodiment of the invention, the air after passing through the first heater core 211 mainly flows to the first passage communicating with the defroster air outlet 204 a. However, the air after passing through the first heater core 211 may flow to the first passage communicating with a face air outlet through which air is blown toward an upper side of the vehicle compartment. Thus, relatively low-temperature air can be blown toward an upper side of the vehicle compartment or the windshield, while relatively high-temperature air can be blown toward a lower side of the vehicle compartment.

Alternatively, in a case where only a driver is seated on the driver's seat of the vehicle and no other passenger is on the seat other than the driver's seat of the vehicle, the relatively high-temperature air after passing through the second heater core 221 can be blown toward the driver of the vehicle compartment, and the relatively low-temperature air after passing through the first heater core 211 can be blown toward the seats other than the driver's seat in the vehicle compartment.

(5) In the above-described sixteenth to twenty-first embodiments, only the coolant for cooling the cylinder head 231 flows out of the first coolant outlet 231 b of the engine 230. However, a part of the coolant for cooling the cylinder block 232 may be mixed with the coolant for cooling the cylinder head 231, and the mixed coolant may flows from the first coolant outlet 231 b of the engine 230 to the first heater core 211. That is, the coolant mainly cooling the cylinder head 231 in the engine 230 may flows out of the first coolant outlet 231 b of the engine 230 to the first heater core 211.

Similarly, in the above-described sixteenth to twenty-first embodiments, only the coolant for cooling the cylinder block 232 flows out of the second coolant outlet 232 b of the engine 230. However, a part of the coolant for cooling the cylinder head 231 may be mixed with the coolant for cooling the cylinder block 232, and the mixed coolant may flows from the second coolant outlet 232 b of the engine 230 to the second heater core 221. Thus, the coolant mainly cooling the cylinder block 232 in the engine 230 may flows out of the second coolant outlet 232 b of the engine 230 to the second heater core 221, while the coolant mainly cooling the cylinder head 231 in the engine 230 may flows out of the first coolant outlet 231 b of the engine 230 to the first heater core 211. Even in this case, the temperature of the coolant flowing out of the second coolant outlet 232 b in the engine 230 can be made higher than the temperature of the coolant flowing out of the first coolant outlet 231 b in the engine 230.

For example, a part of the coolant after cooling the cylinder head 231 may be mixed with the coolant after cooling the cylinder block 232 in the engine 230, and the mixed coolant may flow out of the second coolant outlet 232 of the engine 230 to flow into the second heater core 221. Even in this case, the temperature of the coolant flowing into the second heater core 221 can be increased more than the temperature of the coolant flowing into the first heater core 211.

(6) In the above-described sixteenth embodiment, only the coolant flowing out of the second coolant outlet 232 b of the engine 230 flows into the second heater core 221. However, a part of the coolant flowing out of the first coolant outlet 231 b may be mixed with the coolant after flowing out of the second coolant outlet 232 b, and the mixed coolant may flow into the second heater core 221.

Even in this case, the temperature of the coolant flowing into the second heater core 221 can be made higher than the temperature of the coolant flowing into the first heater core 211, thereby effectively increasing the temperature of air to be blown toward the vehicle compartment.

(7) In the above-described sixteenth to the twenty-second embodiments, the flow amount of the coolant flowing through the first heater core 211 is made larger than the flow amount of the coolant flowing through the second heater core 221. However, the flow amount of the coolant flowing through the first heater core 211 may be made equal to the flow amount of the coolant flowing through the second heater core 221

For example, in the structure of the above-described sixteenth embodiment, a part of the low temperature coolant flowing out of the first coolant outlet 231 b of the engine 230 may be joined with the high temperature coolant flowing out of the second coolant outlet 232 b, such that the flow amount of the coolant flowing through the first heater core 211 is equal to the flow amount of the coolant flowing through the second heater core 221.

(8) In the above-described sixteenth to twenty-first embodiments, the air conditioner of the present embodiment may be applied to a vehicle having an internal combustion engine; however, may be applied to a vehicle in which exhaust heat of an equipment other than the internal combustion engine is used as the heat source for the heating. For example, a heat generating member that generates heat when being operated may be used instead of the internal combustion engine.

(9) In the above-described embodiments, the coolant is used as a cooling fluid for cooling a heat generating member such as an engine mounted to a vehicle. However, as the cooling fluid, a cooling liquid other than water or a gas fluid may be used without being limited to the coolant.

(10) The above described embodiments may be suitably combined if there is no contradiction therebetween.

Such changes and modifications are to be understood as being within the scope of the present invention as defined by the appended claims. 

1. An air conditioner for a vehicle provided with a driving unit for a vehicle traveling, the air conditioner comprising: first and second heating heat exchangers disposed to heat air to be blown into a vehicle compartment by using a cooling fluid for cooling the driving unit as a heat source, the second heating heat exchanger being arranged downstream of the first heating heat exchanger in an air flow to heat air after passing through the first heating heat exchanger; a heater disposed to heat the cooling fluid flowing to the second heating heat exchanger, in the first and second heating heat exchangers; and a controller for controlling a temperature of air to be blown into the vehicle compartment, the controller outputs an operation request signal to the driving unit when a temperature of the cooling fluid is lower than a predetermined temperature, wherein the first and second heating heat exchangers are arranged in parallel with respect to a flow direction of the cooling fluid, and the controller controls a flow amount of the cooling fluid flowing into the second heating heat exchanger to be smaller than a flow amount of the cooling fluid flowing into the first heating heat exchanger when the heater heats the cooling fluid flowing to the second heating heat exchanger.
 2. The air conditioner according to claim 1, wherein the first and second heating heat exchangers are configured such that a flow resistance of the cooling fluid flowing in the second heating heat exchanger is higher than a flow resistance of the cooling fluid flowing in the first heating heat exchanger.
 3. The air conditioner according to claim 1, further comprising a flow adjustment unit that is configured to reduce the flow amount of the cooling fluid flowing into the second heating heat exchanger when the heater is turned on to heat the cooling fluid flowing into the second heating heat exchanger, as compared with that when the heater is turned off.
 4. The air conditioner according to claim 1, further comprising a sensible heat exchanger that is configured to move heat from the cooling fluid downstream of the second heating heat exchanger to the cooling fluid upstream of the heater.
 5. The air conditioner according to claim 1, wherein the driving unit includes an electrical motor for a vehicle traveling, and the heater is an electrical heater which uses a high-voltage electrical source for supplying electrical power to the electrical motor, as an electrical source.
 6. The air conditioner according to claim 1, wherein the heater is a heat generator, which is mounted to the vehicle separately from the driving unit, and generates heat when being operated.
 7. The air conditioner according to claim 6, wherein the heat generator is an inverter which converts an electrical current supplied to the electrical motor.
 8. An air conditioner for a vehicle provided with a driving unit for a vehicle traveling, the air conditioner comprising: a heating heat exchanger disposed to heat air to be blown into a vehicle compartment by using a cooling fluid for cooling the driving unit as a heat source; a controller for controlling a temperature of air to be blown into the vehicle compartment, the controller outputs an operation request signal to the driving unit when a temperature of the cooling fluid is lower than a predetermined temperature; a heat absorbing portion configured to absorb heat from the cooling fluid; a heat radiating portion configured to radiate heat to the cooling fluid; and a pump portion configured to pump heat from the heat absorbing portion to the heat radiation portion.
 9. The air conditioner according to claim 8, wherein the pump portion is a Peltier element that includes a heat absorbing surface thermally connected to the heat absorbing portion, and a heat radiating surface thermally connected to the heat radiating portion, and the Peltier element absorbs heat from the heat absorbing surface and radiates heat from the heat radiating surface when direct current is applied to the Peltier element.
 10. The air conditioner according to claim 8, wherein the heating heat exchanger is a heat exchanger in which the cooling fluid flowing therein is heat exchanged with air passing therethrough so as to heat air, the heat absorbing portion is disposed downstream of the heating heat exchanger in a flow direction of the cooling fluid, to absorb heat from the cooling fluid flowing out of the heating heat exchanger, and the heat radiation portion is disposed upstream of the heating heat exchanger in the flow direction of the cooling fluid, to radiate heat to the cooling fluid flowing into the heating heat exchanger.
 11. The air conditioner according to claim 10, wherein the heating heat exchanger includes a first, heater core for heating air, and a second heater core disposed to heat air after passing through the first heater core, the heat absorbing portion is disposed downstream of the second heater core in the flow direction of the cooling fluid to absorb heat from the cooling fluid flowing out of the second heater core, and the heat radiating portion is disposed upstream of the second heater core in the flow direction of the cooling fluid to radiate heat to the cooling fluid flowing into the second heater core.
 12. The air conditioner according to claim 11, wherein the first and second heater cores are arranged in parallel with respect to the flow direction of the cooling fluid.
 13. The air conditioner according to claim 10, further comprising a heat exchanger disposed to perform heat exchange between the cooling fluid before flowing into the heat radiating portion, and the cooling fluid before flowing into the heat absorbing portion at a position downstream of the second heater core in the flow direction of the cooling fluid.
 14. The air conditioner according to claim 10, further comprising a first bypass passage through which a part of the cooling fluid before flowing into the heat radiating portion is introduced into the heat absorbing portion without performing heat exchange with air in the second heater core.
 15. The air conditioner according to claim 10, further comprising a second bypass passage through which a part of the cooling fluid upstream of the heat radiating portion is introduced to the driving unit while bypassing the heat radiating portion and the heat absorbing portion.
 16. The air conditioner according to claim 8, further comprising: a first fluid circuit in which the cooling fluid of the driving unit is circulated; and a second fluid circuit independently provided from the first fluid circuit, in which a fluid heated by the cooling fluid is circulated to flow into the heating heat exchanger.
 17. An air conditioner for a vehicle having an internal combustion engine, the air conditioner comprising a heating heat exchanger configured to heat air to be blown into a vehicle compartment, by using a first fluid for cooling the internal combustion engine and a second fluid having a temperature higher than the first fluid, as a heat source, wherein the heating heat exchanger includes a first heat exchanging portion in which the first fluid or a mixture of the first fluid and the second fluid flows, and a second heat exchanging portion in which a fluid that is mainly the second fluid and has a temperature higher than a fluid flowing into the first heat exchanging portion flows, and the first heat exchanging portion and the second heat exchanging portion are integrated to form a space therebetween.
 18. The air conditioner according to claim 17, wherein the second heat exchanging portion is arranged downstream of the first heat exchanging portion in an air flow direction.
 19. The air conditioner according to claim 17, wherein the first heat exchanging portion and the second heat exchanging portion are arranged in parallel with respect to an air flow direction.
 20. The air conditioner according to claim 17, wherein the first heat exchanging portion has a heat exchanging area in which air is heat exchanged with the fluid, and the heat exchanging area of the first heat exchanging portion is larger than the heat exchanging area of the second heat exchanging portion.
 21. The air conditioner according to claim 17, wherein the first heat exchanging portion and the second heat exchanging portion are arranged such that a flowing amount of the fluid flowing in the first heat exchanging portion is larger than that flowing in the second heat exchanging portion.
 22. The air conditioner according to claim 17, wherein the first heat exchanging portion and the second heat exchanging portion are configured to have respective fluid passages that are independent from each other.
 23. The air conditioner according to claim 17, further comprising an air conditioning case in which the first heat exchanging portion and the second heat exchanging portion are disposed, the air conditioning case has a first air outlet from which air only having passed through the first heat exchanging portion is blown toward an inner surface of a windshield of the vehicle, and a second air outlet from which air having passed through the second heat exchanging portion is blown toward a passenger in the vehicle compartment.
 24. The air conditioner according to claim 17, wherein the first fluid is a cooling fluid for cooling a cylinder head of the internal combustion engine, and the second fluid is a cooling fluid for cooling a cylinder block of the internal combustion engine.
 25. The air conditioner according to claim 17, wherein the first fluid is a cooling fluid for cooling the internal combustion engine, and the second fluid is a cooling fluid for cooling a heat generation member that is an equipment mounted to the vehicle and is different from the internal combustion engine. 